Call it a weakness, call it a fatal flaw, call it what you will—but nearly every MLB team enters 2013 with an Achilles' heel.
They vary in size and scope, but each one, if exposed, could ruin even the best laid plans and derail a team's entire season if not quickly addressed and remedied.
With Opening Day in the rearview mirror and the regular season underway, let's take a look at what fans and teams alike should be on the lookout for.
Injuries happen to every team, and there are few teams in baseball with as much depth to weather the storm as the Arizona Diamondbacks.
That said, some injuries have a way of sticking around for quite some time—not keeping a player out of the lineup, but negatively impacting his ability to perform to the best of his ability.
The Diamondbacks start the regular season with five players on the disabled list, including a pair of starting outfielders in center fielder Adam Eaton and right fielder Cody Ross.
Last year's most pleasant surprise for the Diamondbacks, left-handed starter Wade Miley, missed a start in spring training with arm fatigue, but he bounced back in his final tuneup of the exhibition season and told MLB.com's Steve Gilbert that he feels fine.
Left fielder Jason Kubel battled a left knee issue for much of the spring, and it was only last week that he rolled his left ankle. While manager Kirk Gibson told Gilbert that he's not overly concerned about the veteran's status, carrying around a banged up leg is not the ideal way for Kubel to enter the season.
Should these injuries hang around for much of the season, it will seriously test Arizona's depth—and put a serious crimp in the team's efforts to return to the playoffs.
For the first time in nearly 20 years, Chipper Jones will not be sitting in the Atlanta Braves clubhouse, leaving a void in leadership that is not easily filled.
That's more of a testament to Jones and his status as one of the iconic figures of his generation rather than a knock against the 25 players who comprise Atlanta's 2013 roster, as Jones has forgotten more baseball than any of them—or us—could ever hope to know.
That's not to say that the team is completely devoid of veterans capable of stepping up in Jones' absence. Tim Hudson and the currently injured Brian McCann, both entering their ninth season with the Braves, serve as the longest-tenured members of the club and are capable of helping to fill the void.
But they can't do it alone, and other players will need to step up and assume a leadership role if Atlanta is to live up to the lofty expectations that many have put upon the squad in 2013.
Baltimore's decision to let Mark Reynolds depart via free agency and insert Chris Davis as the everyday first baseman remains one of the more puzzling ones that I've seen in recent memory.
Not only does it weaken Baltimore's defense, but it shortens the team's bench; something made even more of an issue when Wilson Betemit, expected to be the team's everyday designated hitter, suffered a torn PCL in his right knee late in spring training and will be out for six to eight weeks.
That leaves Nolan Reimold and Steve Pearce, who amazingly enough have both played in a total of 246 major league games over the course of their careers, and who own a combined 49 big league home runs.
Sure, with extended playing time, both are capable of reaching double digits, but in the ultra-competitive AL East, that lack of a consistent power source from the DH spot could be the difference between first and last place.
With the chaos of the last 18 months firmly in the past, Boston will try and get things back on track in 2013, which, while it may not include a return to the postseason, will certainly include a return to respectability.
Much of the team's success—or lack thereof—will be tied to the starting rotation.
You simply don't know what you can count on from John Lackey, who missed all of 2012 after undergoing Tommy John surgery, so let's take him out of the equation for a second.
Of the remaining four pitchers in the rotation, Clay Buchholz, Ryan Dempster, Felix Doubront and Jon Lester, the group pitched to a combined 1.98 ERA and 0.94 WHIP this spring, walking 23 and striking out 78 over 86.1 innings of work.
Buccholz and Lester went 6-0 with a 0.77 ERA and 0.64 WHIP in 46.2 innings of work, while Dempster and Doubront had a combined 3.40 ERA and 1.29 WHIP, throwing 39.2 innings.
There's enough talent on the rotation for the team's regular season numbers to resemble what the Double-D's put together this spring, but the inconsistent performances of the past make you think twice about the group being able to put it all together at the same time.
With youngsters like Rubby De La Rosa and Allen Webster waiting in the wings, early struggles could force the team's hand and find one of those starters throwing out of the bullpen.
Luis Valbuena shouldn't be starting for any team.
With the perennially disappointing Ian Stewart is on the 15-day disabled list with an injured left quad and former first round pick Josh Vitters continuing to be a defensive disaster at third base, the Chicago Cubs are left with no other option than to turn to light-hitting utility infielder Luis Valbuena to handle third base.
That's not a good thing.
Nobody's going to bash the Cubs for not making a stronger push to keep Aramis Ramirez, the team's former All-Star third baseman who defected to the division-rival Milwaukee Brewers via free agency before last season, but the team clearly has no real options with which the fill the gaping hole Ramirez left.
Vitters may eventually be able to do just that, but it won't be during the 2013 season.
The Tyler Flowers era—or "error," depending on how things play out—gets underway in earnest on the north side of Chicago this year, and there's one thing that's pretty clear.
With a career slash line of .205/.307/.388 in 273 at-bats over parts of four big league seasons, Flowers doesn't have the offensive capabilities or experience behind the plate of the departed A.J. Pierzynski, who handled things behind the plate for the White Sox for the past eight seasons.
No longer a up-and-coming prospect at the age of 27, Flowers needs to deliver if the White Sox are to remain in contention in what is going to be a far more hotly contested AL Central than they are used to playing in.
If Flowers falters or gets injured, the White Sox are in trouble, for Chicago has no other viable alternatives.
Hector Gimenez, 30, has some pop in his bat, but is a career backup with 11 big league games on his resume, while Josh Phegley, 25, has yet to prove that he can hit Triple-A pitching consistently.
It's all smiles in Cincinnati.
It might sound like a cop-out, but go ahead and point to the Achilles' heel on the Cincinnati Reds this season.
It's definitely not the bullpen, where the team has a pair of All-Star closers in Jonathan Broxton and Aroldis Chapman, along with one of the best setup men around in Sean Marshall.
The starting rotation has a pair of aces in Johnny Cueto and Mat Latos, both well below the age of 30, and the lineup is explosive, especially the top half.
With solid backups at nearly every position and minor league depth to handle any short-term injuries, it would take a catastrophic injury to one of the team's biggest stars to derail what is sure to be another successful season at Great American Ballpark.
No surprise here, the Cleveland Indians starting rotation is going to derail what looks to be—on paper, at least—a very dangerous lineup capable of putting runs on the board.
I wrote as much a few months back, shortly after the Indians had signed Nick Swisher as a free agent, and neither the additions of Scott Kazmir or Brett Myers (or Trevor Bauer or Daisuke Matsuzaka, for that matter) are reason enough to change my stance.
Justin Masterson and Brett Myers are capable of turning in solid seasons, but Ubaldo Jimenez, me thinks not.
It's been three years since Jimenez posted a winning a record or an ERA below 4.45, yet the expectations remain that someone will snap their fingers and the 26-year-old that won 18 games for the Colorado Rockies in 2010 is going to appear on the mound in an Indians uniform.
It's not going to happen.
Kazmir is a nice story, but that the Indians are counting on a guy who has thrown less than two major league innings since the end of the 2010 season tells you everything you could possibly need to know about the sorry state of the starting staff in Cleveland.
Jorge De La Rosa.
Where the Cleveland Indians at least added some pieces to the rotation, Colorado, with a starting staff that posted a MLB-worst 5.81 ERA in 2012, is relying on old faces to rebound from injury.
Jhoulys Chacin, Jorge De La Rosa and Juan Nicasio made a combined 54 starts for the Rockies in 2011, going 20-20 with a 3.71 ERA and 1.31 WHIP—respectable numbers for anyone, especially a team that calls Coors Field home.
The trio combined to make only 28 starts in 2012 with drastically different results, going 5-11 with a 5.16 ERA and 1.63 WHIP.
Asking that trio to return to its 2011 form may simply be asking too much—and the Rockies lack the quality minor league pieces to pick up the slack should injury or ineffectiveness kick in.
Bruce Rondon might be the long-term solution in the ninth inning for the Detroit Tigers, but he proved beyond a shadow of a doubt in spring training that he's not ready to close games for a contending team.
So, the Tigers will go with a closer-by-committee approach, one that, sooner or later, is going to prove costly and demand that Detroit find a singular answer for the ninth inning. Not having a full-time closer weakens the bullpen, and it robs Detroit of some of its depth.
In the grand scheme of things, the worst baseball player on Houston's roster would look like Babe Ruth or Sandy Koufax if put on the same diamond as the rest of us mere mortals.
But when compared to the rest of the teams in MLB, Houston's roster leaves plenty to be desired.
While winning the team's first game as a member of the American League—over their in-state rivals, the Texas Rangers nonetheless—was a great way to start the season, Houston simply doesn't have the top-end talent on its roster that is necessary to compete over the course of a 162-game schedule.
Sooner, rather than later, Houston's 2013 season will begin to unravel as a result.
I'm not disputing that Kansas City's starting rotation in 2013 is vastly improved from the group that the team trotted out only a year ago.
But before we start anointing the team's rotation as one of the best in baseball, it's important to remember that not so long ago, some of these pitchers weren't very good.
Of the group, only Wade Davis and Luis Mendoza have not posted ERA's above 5.00 in their careers as full-time starting pitchers.
James Shields posted a 5.18 ERA for Tampa Bay in 2010. Jeremy Guthrie had a 5.04 mark for Baltimore in 2009, and had pitched to a 6.35 ERA with Colorado in the first half of the 2012 season before turning things around with the Royals.
Three times, Ervin Santana has broken that plateau: in 2007 (5.76), 2009 (5.03) and 2012 (5.16).
I don't expect any of the Royals starters to finish the season with numbers anywhere near as bad as those, but that they have pitched as poorly as this before—and that those seasons didn't come all that long ago—is something to keep in mind.
Thankfully for the Los Angeles Angels, spring training numbers mean little when it comes to regular season success.
Because aside from Joe Blanton, who pitched to a 3.46 ERA and 1.00 WHIP in exhibition play, the group was terrible, with a combined 6.81 ERA, allowing 51 hits over 39.2 innings of work.
Despite a continuing decline in his velocity, Jered Weaver remains one of the best starting pitchers in baseball, while C.J. Wilson, Tommy Hanson and Jason Vargas all have the skills to be solid, middle-of-the-rotation arms.
They have done it before.
Yet even with a high-powered lineup that will put runs on the board in bunches, the Angels starting rotation, if not pitching at the top of their individual games, has the potential to keep the team from reaching its potential in 2013.
Defense is often overshadowed by gaudy offensive numbers, but it's as important a part of the game as putting runs on the board or a pitcher shutting down the opposition.
For the Los Angeles Dodgers, 2013 promises to be a bit of a wild ride defensively, especially on the left side of the infield, where Hanley Ramirez and either Luis Cruz, Justin Sellers or someone else will take to the field on a daily basis (once Ramirez returns from a torn ligament in his right thumb.
Ramirez, more than anyone else, is a defensive liability at either shortstop or third base, whichever spot manager Don Mattingly ultimately decides to play him at. Both Cruz and Sellers are adequate with the glove, but neither one is going to be in the running for a Gold Glove award.
Should the defense begin to break down and cost the Dodgers some games, it could ultimately be the difference between making the playoffs and not.
When it comes to the 2013 edition of the Miami Marlins, there's Giancarlo Stanton, Ricky Nolasco, a handful of quality relievers and not much else.
Youngsters like catcher Rob Brantly and starting pitcher Jose Fernandez offer hope for the future, but the Marlins lack the major league talent needed to compete—much like the Houston Astros.
This, of course, isn't a surprise to anyone, after the team conducted its second fire-sale of talent this past winter under the watchful eye (and tightening wallet) of owner Jeffrey Loria.
Different year, same story for the Milwaukee Brewers.
John Axford blew his first save chance of the season on Opening Day, squandering Milwaukee's one-run lead over the Colorado Rockies by serving up a two-out, game-tying home run to Dexter Fowler in the ninth inning.
While the Brewers would go on to win the game—and even the greatest closers in the game blow saves from time-to-time—that Axford once again failed to work a flawless ninth inning only brings the bullpen's struggles from 2012 back to the forefront, when the group had the worst ERA in MLB.
If Axford continues to falter, the Brewers will have no choice but to replace him—lest the team allow the bullpen to once again sabotage a chance at reaching the postseason once again.
Minnesota's starting rotation is better than it was a year ago, but there is still plenty of work to be done before the unit ranks in the top half of MLB in terms of effectiveness and potential.
Acquiring Vance Worley from the Philadelphia Phillies this past offseason was a good start at reaching that goal, but he's badly miscast as the ace of the staff—at best, Worley is a middle-of-the-rotation arm, a back-of-the-rotation arm on a contending team.
The rest of the staff is comprised of journeymen, retreads and unproven semi-prospects; Kevin Correia, Cole De Vries, Liam Hendriks and Mike Pelfrey aren't striking fear into the hearts of opposing batters when they step to the plate against Minnesota.
Scott Diamond's eventual return from offseason elbow surgery will help, but like Worley, Diamond is a middle-of-the-rotation arm who will be asked to carry far too heavy a load for the Twins.
So far, so good for New York's newly rebuilt outfield, as Marlon Byrd and Collin Cowgill combined to go 4-for-10 with three runs scored and six RBI against the San Diego Padres on Opening Day.
But one game doesn't make a season.
Byrd is coming off of one of the worst seasons of his career, hitting .210 with an OPS below .500 in 47 games for the Washington Nationals and Boston Red Sox, while Cowgill has been a fourth outfielder/platoon player for most of his big league career.
Duda, who has tremendous power, swings and misses more often than he makes contact, and his defense is questionable at best.
Should the trio slump badly or suffer an injury, the Mets are ill-equipped to make up for that loss.
No team in baseball has been hit harder by the injury bug than the New York Yankees.
First baseman Mark Teixeira, shortstop Derek Jeter and third baseman Alex Rodriguez all began the season on the disabled list, leaving second baseman Robinson Cano as the only everyday infielder left in the lineup.
Center fielder Curtis Granderson joined the group of the hobbled, along with starting pitchers Phil Hughes and Michael Pineda, who has yet to throw a regular season pitch in a Yankees uniform more than a year after the team traded a pair of prospects, including Jesus Montero, to acquire him.
With the exception of Rodriguez and Pineda, none of these injuries are expected to be a lingering problem throughout the season.
But just because nobody expects them to be an issue doesn't mean that they won't be—and with no high-end prospects ready to contribute at the big league level, it may only take a nagging injury to one of the team's stars to derail the season.
Yoenis Cespedes is the real deal, and somehow, Coco Crisp continues to put up solid numbers atop Oakland's lineup despite his obituary as a productive, everyday player being written years ago.
But after those two, Oakland's lineup is dependent on role players playing above their heads, players who broke out in 2012 building on their former success and a whole lot of luck.
Can Josh Reddick, who had a total of nine career home runs in parts of three major league seasons, hit 32 home runs again?
Can Jed Lowrie, with a total of 19 career home runs in parts of four major league seasons, go deep 16 times in 2013 as he did in 2012?
Fair or not, a team needs some legitimate power if it hopes to contend in the supercharged American League, especially in the AL West, where everyone except for the Houston Astros has multiple players who are locks to put up 20-plus home runs on the season.
If Oakland's bats regress back to their pre-2012 forms, the A's simply may not have the power necessary to successfully defend its division title.
I think we can all agree that in order for a team to contend, it needs at least three quality starting pitchers in the rotation.
Philadelphia most definitely has two, in Cole Hamels and Cliff Lee.
Yet what was unthinkable only two years ago has become closer to being a reality—that Roy Halladay may actually hinder, not help, Philadelphia's chances of returning to the playoffs.
Halladay simply hasn't looked like the same pitcher who, from 2002 through 2011, went 170-75 with a 2.97 ERA and 1.11 WHIP, winning a pair of Cy Young Awards along the way.
His velocity has been on the decline since last season, when a shoulder injury kept him on the shelf for a bit and seemed to never fully heal.
Whether it's the wear and tear that Halladay has put on his arm over the years or an injury that nobody's talking about, the 36-year-old did nothing this spring to make you believe that he's back on track and able to shut down opposing lineups.
If Halladay isn't right, the Phillies playoff chances take a significant hit.
Really, I could have titled this slide "Everyone in Pittsburgh's lineup not named Andrew McCutchen," as that would be a more accurate depiction of what could send the Pirates to their 800th consecutive losing season.
(OK, it hasn't been that long, but it's been more than 20 years since the Pirates last saw a winning record or the postseason).
Pittsburgh desperately needed to add another big bat to compliment and protect All-Star center fielder Andrew McCutchen in the lineup and failed to do so, leaving the likes of Pedro Alvarez, Garrett Jones and Neil Walker from trying to keep teams from simply pitching around McCutchen.
Not giving McCutchen a pitch to hit is the quickest path to success for Pittsburgh's opposition, and unless the team's secondary players can produce more than they have in the past, the losing streak will continue.
San Diego has a solid lineup, one that has a solid mix of established veterans and up-and-coming youngsters, and a bullpen that ranks somewhere in the middle among MLB teams.
But when it comes to starting pitching, that's an entirely different story.
Edinson Volquez gets shelled away from Petco Park—we only need look at San Diego's 11-2 loss at the hands of the New York Mets on Opening Day for the most recent proof of that. But he's not the only Padres starter who fails to deliver when the team takes its act on the road.
In 2012, Padres starters pitched to a 3.35 ERA and 1.27 WHIP at home, a 4.73 ERA and 1.38 WHIP on the road.
If the team's starting rotation continues to struggle badly away from Petco Park, it's going to be another long season in San Diego.
Buster Posey will be asked to carry a heavier load for the defending World Series Champions in 2013 than he was last season, and there's little reason to think that the reigning NL MVP isn't capable of doing just that.
But he needs help, while Hunter Pence and Pablo Sandoval are quality players, they are complimentary pieces, Neither one is the big, impact bat that many expected the Giants to go out and acquire this past winter.
Yet the Giants decided to stick with what they know, re-signing Angel Pagan and Marco Scutaro in the hopes that they can keep their incredibly high level of production in the 2012 playoffs going throughout the regular season.
If age and mediocrity begin to show for some of the team's more important pieces, it won't matter how good of a pitching staff the team has—it will find itself passed in the standings by the likes of the Arizona Diamondbacks and Los Angeles Dodgers.
Among American League teams, Seattle has ranked dead last in runs scored in each of the past three seasons, and the Mariners did address that ugly fact this winter.
Adding Kendrys Morales and Mike Morse, among others, to the mix in Seattle will certainly help, and we saw some early results this spring, as the team was one of the more prolific offenses in baseball.
But there's cause for concern.
Not only does Seattle need newcomers like Morse and Morales to contribute, but it needs the core of youngsters on the team: Dustin Ackley, Jesus Montero and Justin Smoak to finally step up and produce the big numbers that everyone believes the trio is capable of doing.
Anything less than that will result in mediocre results for Seattle in 2013, and put the team no closer to finding a long-term solution for its run-scoring issues than it was at the end of 2012.
Adam Wainwright is healthy and back to lead the starters in St. Louis, while Jake Westbrook provides a solid veteran presence at the back of the rotation.
But after that, the Cardinals rotation is far from a sure thing, especially with the departure of Kyle Lohse via free agency and Chris Carpenter's shoulder injury that has him out for an undetermined period of time.
Jaime Garcia battled injury and ineffectiveness last season, while Lance Lynn and Shelby Miller both have upside, but are largely untested at the major league level.
While the Cardinals have some additional pieces who can step in and help if needed, like Joe Kelly and Trevor Rosenthal, they too are largely untested and unproven in the big leagues.
For a team that expects to contend, the starting rotation could be the Cardinals undoing.
Tampa Bay has done a terrific job in recent years by remaining in contention without having a big, impressive lineup to lean on for run support.
These days, the only two sure things in the team's lineup are Evan Longoria and Ben Zobrist—and counting on Longoria to stay healthy enough to contribute is a risking proposition at best.
The eventual promotion of top prospect Wil Myers to the mix should help Tampa Bay put more runs on the board, but the team needs someone else to step up and become a legitimate run producer in the middle of the lineup.
Without that happening, the Rays will continue to be nothing more than a middling offense with really good pitching.
Despite Matt Harrision's less-than-stellar performance on Opening Day against the Houston Astros, the Texas Rangers shouldn't have much concern over the front of the starting rotation.
Harrison, Yu Darvish and Derek Holland are capable pitchers who will provide quality innings and give the team a chance to win more often than not.
Alexi Ogando is a solid pitcher but is best suited for the bullpen, while the team's other options for the final two spots in the rotation, Colby Lewis and Martin Perez, are both on the disabled list with uncertain return dates.
Not being able to land a front-of-the-rotation arm like Zack Greinke or a complimentary piece like Kyle Lohse could come back to haunt Texas this season.
For all of the major additions that Toronto made during the offseason, the team's bullpen remains a unit that is in flux and trails behind the rotation and lineup in terms of quality and production.
Case in point: Darren Oliver, 42, is probably the team's most reliable reliever—not the worst thing in the world, but considering his age and that he's unlikely to work more than an inning at a time, much will be needed from the rest of the group.
Casey Janssen and Sergio Santos are both recovering from shoulder surgery, leaving unanswered questions about just how effective they'll be.
Steve Delabar and Esmil Rogers can both blow the ball past batters, but neither one is a dominating reliever. Brett Cecil has been mediocre since his days as a starting pitcher...well, you get the idea
Despite a vastly improved roster, if Toronto's bullpen falters during the season, the Blue Jays won't be winning the division, much less the World Series, as some have predicted that they will.
When the 2012 season came to an end, the Washington Nationals had four left-handed relievers at its disposal: Sean Burnett, Zach Duke, Tom Gorzelanny and Mike Gonzalez.
At the start of the 2013 season, only Duke remains—and that lack of a second quality left-handed option out of the bullpen is the only real weak spot on a Washington squad that is expected to make a deep playoff run this season.
It's really nitpicking at this point, because let's be honest—having only one left-handed reliever in the bullpen isn't going to derail anyone's season.
But the Nationals simply don't have a major weakness—and that's bad news for the rest of the National League.