Halladay's right shoulder could end his career.
"All good things must come to an end" may come off as insulting in an exchange between a prospect and a veteran, yet the idiom rings true for many aging players.
Outliers like Jamie Moyer (49) and Tim Wakefield (45), Julio Franco (48) and Omar Vizquel (45) slowly age to become athletic dinosaurs but remain productive until their last baseball breath.
For the majority of ballplayers, however, the wear and tear of a 162-game season takes a toll on ones body. Eventually, the childhood dream of throwing the final out of the World Series or hitting a walk-off grand slam has either been accomplished or missed.
The ever-rotating carousel of baseball talent continues to churn out the next Cy Young winner and batting champ; and it will carry on as long as the great sport of baseball lives.
The following five veterans are trending downwards and may be replaced before season's end.
Can Marcum improve his control before a mid-June series with the Braves?
Shaun Marcum may not be a veteran in the extreme sense of the word, but with seven professional years under his belt and on his third team in four years, Marcum will be fighting to maintain his rotation spot all season.
As the New York Mets struggled through the first month of the season, Marcum followed suit to an 0-2 record and a 7.20 ERA. In his two starts, the former Blue Jay and Brewer has failed to escape the fifth inning and has compiled nearly as many walks (six) as strikeouts (eight).
He also performed an emergency relief appearance in a 15-inning game against the Miami Marlins on April 29, taking the loss in 1.2 innings pitched (four hits, two runs, and a walk).
On the other hand, Mets' top pitching prospect Zack Wheeler has found his groove in Triple-A Las Vegas after a rocky start to the 2013 campaign.
Over his last two starts, Wheeler has a 2-0 record and a 0.71 ERA in 12.2 innings. He has allowed just eight hits and struck out 12 batters over that same span. That's a vast improvement from his first five starts of the season when he went 0-1 with a 5.79 ERA, walking 15 batters compared to just two base on balls in his last two starts combined.
Shaun Marcum has a proven track record at the major league level with a 57-38 lifetime win-loss record and a 3.80 lifetime ERA.
According to Matt Musico of Yahoo! Sports, the perfect time for Wheeler's debut is fast approaching — a five-game road series against the Atlanta Braves from June 17-20.
Marcum has a lot to prove.
Harang has had just one win-loss percentage above .500 since 2007.
Despite an NL Cy Young campaign with the Cincinnati Reds in 2007, Aaron Harang's team knew something was wrong over the next two seasons. During that miracle season six years ago, Harang went 16-6, throwing 231.2 innings, striking out 218 and leading the league K/BB ratio (4.19).
In 2008 and 2009, conversely, Harang went a combined 12-31 with a 4.52 ERA and watch his innings pitched and strike out totals take a drastic decline.
In 2013, the numbers haven't gotten any better for the 12-year veteran with a 1-3 record and an 8.68 ERA. Other than his latest start for the Seattle Mariners when he lasted six innings, Harang hasn't gone more than five innings in any of his other three starts, allowing six home runs combined during those appearances.
The Mariners currently sit in third place in the AL West with a 15-19 record, but if they fall behind the Los Angeles Angels as the season progresses, the team may choose to promote Taijuan Walker from Double-A Jackson.
Walker needs to improve his accuracy thereby cutting back on his walk totals, but the youngster could make the jump to the majors after a brief stint at Triple-A Tacoma. After a rough first outing of the season, the right-hander has allowed just two earned runs in his last 30 innings pitched while striking out 31 batters.
It's just a matter of time before Walker gets the call to Tacoma, so Harang better watch his back.
Bundy is considered by many to be the top pitching prospect in baseball.
Unlikely but worth noting, Freddy Garcia may have a bundle to worry about in the near future.
Garcia was dropped by the San Diego Padres a week before the regular season began, and the Baltimore Orioles decided to take a chance on the 36-year-old. His career has spanned three decades, beginning in 1999, yet he still believes he can be a contributing factor to a major league club.
Garcia proved that in his first start for the Orioles as their No. 5 starter, throwing 6.2 innings and allowing just two runs on three hits and collecting his first win of the season.
Just how long Garcia's arm will hold up is the question. The native Venezuelan could easily eclipse 200 innings, doing it seven times in his first 10 seasons, but hasn't accomplished the feat since 2006.
Meanwhile, the same question can be applied to top pitching prospect Dylan Bundy, who recently received a platelet-rich-plasma injection (PRP) in his right elbow and is out of commission for at least six weeks.
Bundy impressed at Single-A and high Single-A last season in the Orioles organization, making a combined 20 starts and striking out 106 batters in 87 innings on his way to a 1.86 ERA. The success continued with a 3.24 ERA in 16.2 innings at Double-A Bowie.
It's a matter of health for both starting pitchers, but with each trending in opposite directions — Bundy up, Garcia down — who knows when the transition may come.
No one ever wants to see the demise of a pitcher like Halladay. He was too fun to watch.
The 2013-version of Roy Halladay is a far cry from the former two-time Cy Young award-winning Halladay who walked over hitters like he was stealing their lunch money.
Over 34.1 innings in 2013, Halladay has allowed 33 earned runs, surrendered nine home runs, walked 17 batters and hit four. His WHIP stands just below 1.50.
From 2008 to 2011, Halladay finished in the top five of the Cy Young voting in his respective leagues, winning it in 2010 with the Philadelphia Phillies when he went 21-10. He threw nine complete games and collected over 250 innings of work.
Now officially on the 15-day disabled list with right shoulder inflammation, the Phillies will search for his replacement.
The likely candidate is left-hander Adam Morgan who in 34.2 innings has compiled a 1-2 record and a 3.89 ERA. Morgan has struggled in his last three starts, collecting a 6.89 ERA, after throwing particularly well in his first three of the season when he owned a 1.42 ERA over 19 innings.
Another option would be Tyler Cloyd, who went 12-1 with a 2.35 ERA in 22 starts at Triple-A Lehigh Valley in 2012.
If Halladay can't return to dominate form after his stint on the disabled list, he may choose to call it quits. In which case, one of the most impressive pitching careers of the early 21st century will be in the books.