On every team in the country, there are at least one or a few names on the roster that are a serious injury or off-the-field issue away from crumbling their program's hope for next season.
In some cases, a star player goes down and a young talented guy waiting in the wings steps in and blossoms. Problem solved.
In others, a star player gets knocked out and the season dims.
It all depends on depth, talent, and circumstance.
Let's take a look at the top 25 irreplaceable players for the 2010 season.
The names aren't ranked by talent, they're ranked by their importance to their respective teams and the impact their loss would have to the their team's hopes for success next year.
Derek Wolfe is one of the best run-stoppers in the country and a defensive tackle who takes up a ton of room in the middle of the line.
When you're talking about a team like Cincinnati that basically has a giant question mark on that side of the ball, players like Wolfe mean that much more.
They don't have much depth on the line and no defensive tackles that have half the talent of Wolfe.
Most experts aren't giving the Bearcats much of a chance this season because of all their key personnel losses from a year ago.
Losing Wolfe would pretty much seal the deal.
There aren't many situations quite like the one at Boston College this year.
They just don't have bodies to fill the depth chart at running back.
Beyond Montel Harris, freshman Sterlin Phifer is pretty much the only name on the roster.
Harris' primary backup, Rolandan Finch, tore his ACL in the spring and left the Eagles with serious concerns going into the season.
They know it all too well that if anything happens to Harris their offense will be stuck in the mud quicker than they can blink.
Markelle Martin is the Cowboys' leading returning tackler and is expected to take up one of the leadership roles for the team now that Lucien Antoine has moved on.
Martin should be in line for a breakout season and has the chance to be one of the top defensive backs in the country.
If he stays healthy, Oklahoma State is in good shape.
If he gets hurt the secondary is a mess.
His primary backup, Mathies Long, has three career tackles.
He'll be a prime target of every offense on their schedule without Martin around to cover him.
Now that Jeremiah Masoli is off the team, the offense will have to rely on someone and while LaMichael James will get the bulk of the carries at running back to make up for Masoli's abense, there is depth behind him.
The same can't be said for the Ducks receivers.
Jeff Maehl is the team's best wideout and produced more last season than the next two names of the roster combined.
If he gets injured, the offense would become one dimensional in a heartbeat.
Jacquizz Roders is a Heisman Trophy candidate who rushed for almost 1,500 yards last season.
He's expected to explode next season and should be one of the top rushers in the country.
He's the type of talent that can't be left off this list and while the depth behind him is untested, Jovan Stevenson and Ryant McCants do have potential.
If Rodgers goes down, the team will suffer severely for it, but not to the extent that some experts are predicting.
The offensive line is talented and can survive Rodgers' loss.
The Hurricanes' revival last season had everything to do with the emergence of a potent offense built around quarterback Jacory Harris and a stable of talented receivers.
If Miami is going to continue that success, Harris needs to stay healthy and keep getting his receivers the ball.
He's not the be-all end-all of the team, but starting over with a new QB like A.J. Highsmith would be too much for this young team to handle.
Akeem Ayers is the best player on the Bruins defense and a candidate to be first-team All-American next season.
He's the only returning starter of last year's group of linebackers and the type of playmaking presence that can't be replaced by adding a new name to the mix.
If he goes down, UCLA will be playing next season with an entirely new core of linebackers.
Teams don't generally have success in situations like that.
Georgia Tech's famous triple option offense requires athleticism, speed, timing, skill, and most importantly, experience to run.
Nesbitt runs it to perfection. That can't be denied.
If he were to be lost for the season, the Yellow Jackets would have to turn to Tevin Washington as the starter.
Washington is talented and has a bright future, but there's no way the offense will have a seamless transition to the new QB.
Eric Hagg is the most important player on Nebraska's defense for a number of reasons.
Firstly, he's a playmaker who contributes not only as a safety, but plays time at linebacker as well.
Secondly, he's a team leader entering his senior season expected to be the central point of the defense.
And thirdly, his primary backup, Austin Cassidy, notched only nine tackles last season.
If Nebraska is going to turn some heads in the Big 12, Hagg needs to stay healthy and have another solid season.
Otherwise they might have to rely on Cassidy and there's no guarantee that's going to take them anywhere.
Lawrence Wilson might not be the household name like some of the other players on this list, but he led the Big East in tackles last season and has the type of athleticism and instinct that can't be taught.
On a team that might be a surprise contender for the conference, UConn will need every bit of fire power they can muster and you'll be hard pressed to find another star on that defense with half the resume of Wilson.
Pryor really came into his own late last season and by the end of the year looked like the quarterback he was hyped up to be coming out of high school a couple years ago.
He's the best dual-threat QB in the country and based on the way he closed out his 2009 campaign, he just might be the best player in the country in 2010.
Ohio State has proven they can win when he's playing poorly though, and for that reason he isn't higher on the list.
Michigan has a ton of question marks to address this season, especially along their defensive line and in the secondary.
Right now Troy Woolfolk is the only reliable corner on the roster and one of the best defensive backs in the Big Ten.
The Wolverines struggled to defend against the pass last season, but Woolfolk wasn't the reason to blame for this.
This year the unit has even less depth and a serious injury to Woolfolk would absolutely crush their pass defense.
Scott Tolzien was the most efficient passer in the Big Ten a year ago and while he doesn't have the talent or household name of a Terrelle Pryor or a Ryan Mallett, he's crucial to his team's success.
When your primary backup tears their ACL, like Curt Phillips did this spring, and now the only name behind you is redshirt freshman Jon Budmayris, that makes you a priceless commodity for a team trying to survive in a very competitive Big Ten.
Tolzien doesn't make many mistakes and that's probably his best attribute.
The Badgers can't count on Budmayris to do the same.
DeAndre McDaniel is an All-American cornerback who has more talent and brings more to the table than any other defender on Clemson's roster.
This is a team in transition that needs to find replacements for key losses like C.J. Spiller.
McDaniel is one of the few stars returning to the defense from last season.
The Tigers lost two starters from their secondary in the offseason and if they lose McDaniel, the entire unit is in serious trouble.
There are a few key personnel to look at when thinking of the most valuable players for Iowa, but no one has the make or break factor quite like Ricky Stanzi.
The Hawkeyes might have one won the Big Ten and possibly even been in the mix for the National Championship game if not for his ankle injury last November.
That cost them a game to Northwestern and a tough loss to Ohio State the following week; Iowa's only losses of the season.
They can get by without Stanzi—they've proven that—but they won't accomplish much if he goes down.
Jerrod Johnson was one of the most productive players in all of college football a year ago with over 4,000 total yards.
He can do it all and means an immeasurable amount to his team.
There isn't a true backup on the roster to step in if something were to happen to Johnson besides receiver Ryan Tannehill.
But Tannehill is the team's leading receiver and has very little experience throwing the ball.
Tannehill might be able to get it done, but Johnson's loss would ruin the dynamic of the offense.
Alabama has a lot of talent and a lot of depth at pretty much every position on both sides of the ball, but the one thing they don't have in their secondary is experience.
Besides Mark Barron of course.
He's one of the best safeties in the country and will play a huge role in Alabama's secondary in 2010.
If he goes down, the Tide will be relying on true freshman like Jarrick Williams or Nick Perry to start.
Both of them have talent, but neither can duplicate Barron's production in year one.
A Barron injury could really expose Alabama's secondary.
You could make the claim that Ryan Williams is every bit as valuable to Virginia Tech as Tyrod Taylor is, but try and justify that after taking a look at their backups.
Williams has Darren Evans, Kenny Lewis and David Wilson behind him to take over if anything were to happen to him. Those three are perfectly capable of producing solid production by committee.
Can you say the same for Ju-Ju Clayton or Logan Thomas at quarterback if Taylor goes down?
Didn't think so.
This is a simple choice because if you're a fan of Baylor, you know exactly what the consequences of losing Robert Griffin are.
He emerged as a dangerous weapon as an 18-year-old dual-threat and fueled a lot of hope for Baylor.
Unfortunately, a torn ACL sidelined him for much of last year and ruined the team's season.
He's healthy now and there might not be anything more important to the Bears 2010 season than his right knee.
A.J. Green is arguably the best receiver in the country and a deadly weapon for the Bulldogs.
He's got an ideal size and speed combo that's lacking from any other weapon on the roster.
Green missed three games due to injury last season and the drop off in talent beyond him was pretty serious.
The Bulldogs resorted to dump-off passes against Kentucky and abandoned the passing game all together against Georgia Tech.
That's exactly what would happen if he were to go down again this year.
Patrick Peterson is the top cornerback in the country and the key to the Tigers secondary in 2010.
He's arguably the best cover corner in all of college football, a solid tackler, a leader, and a playmaker who can dictate an opponent's offense like few can.
LSU has depth at corner and one of the best secondaries in the country, but it would all unravel without Peterson.
Instead of having the best cornerback duo in the nation with Peterson and Morris Claiborne, LSU would be forced to move some pieces around and that would disrupt the chemistry of the unit.
A strength could turn to a weakness overnight.
Greg Jones is the heart and soul of the Spartan's defense.
He's one of the top defensive players in the country and has led the team in tackles for each of the last three seasons.
Jones is one-man wrecking ball on the defensive side of the ball and has the type of playmaking ability you just can't teach.
Michigan State has some depth and talent at linebacker, but there's no one who can step in and do what he does; at least not next year.
Stanford did some damage in the Pac-10 a year ago and if it's gong to build off of that production, Andrew Luck is the key.
Like some of other quarterbacks on this list, he's the unquestionable leader of his offense and a franchise-type player who instantly upgrades everyone else around him.
With star running back Toby Gerhart off to the NFL, the Cardinal will rely on their passing game more than ever, and that means a ton of throws for Luck.
They might have some names to toss to the lions if Luck were injured, but it wouldn't help them win any games.
Jake Locker is one of the hot names entering the 2010 season and a candidate to be the first pick in the NFL draft.
He's a superb offensive weapon and pretty much the whole show in Washington.
Not only would you struggle to find a backup who could match half his production and leadership, you'd simply struggle to find a backup on the Huskies roster whose name you knew.
Now that Ronnie Fouch has transferred, Locker's primary backups are a couple of freshman in Nick Montana and Keith Price.
Arkansas might also have Tyler Wilson at quarterback to use in the case of an emergency, but there's only one Ryan Mallett and you just don't replace guys like this.
The playmaking ability he brings to the table can't be reproduced by Wilson or anyone at any position on the Razorbacks roster.
If he goes down, any chance of Arkansas surprising people in the SEC is gone with him.