There is no way to tell just how many innings any particular pitcher can throw over his career. If there were a gauge on pitcher's arms to let teams know just how many pitches were left in those valuable arms, the job of being a GM would be so much easier.
For instance; When the Cliff Lee/Roy Halladay deal eventually becomes final, the Phillies would be giving up Cliff Lee - a pitcher with 1,196 2/3 innings on his arm - for the right arm of Halladay, which has thrown a whopping total of 2,046 2/3 innings, an astounding 850 more innings than Lee. It's interesting, because both pitchers are of similar age, but the mileage on their arms is considerably different.
So just how many innings does the average pitcher get out of their arm?
Well, for Hall of Fame pitchers - and there's no guarantee that either Halladay or Lee will reach Cooperstown, although Halladay seems to be close - the magic number is 3,764. That's the average number of innings for Hall of Fame pitchers. If that's the standard, then Halladay would have roughly 1700 innings left in the tank. Halladay has thrown 1,710 innings since the start of the 2002 season, but keep in mind that he was limited to just 275 combined innings for 2004 and 2005 because of injuries. In 2004, Halladay suffered with a sore right shoulder all season long that landed him on the DL twice during the season. The following year, a line drive off the bat of Kevin Mench broke Halladay's leg, again shortening his season. In other words, even if Halladay were to have the average number of innings in his arm, there shouldn't be any concerns that he can pitch his way through another three or four years, whichever the Phillies wind up guaranteeing.
The Hall of Fame is full of those freak of nature types, who had arms that seemingly were a renewable energy source. Cy Young threw an amazing 7,354 innings in his career, the most of any Hall of Fame pitcher. Walter Johnson, Phil Niekro, Nolan Ryan, Gaylord Perry, Don Sutton, Warren Spahn and Steve Carlton were all over 5,000 innings when their careers ended. Of course, you need to note that some of those pitchers - primarily Carlton - limped through the final couple hundred innings of their careers. For what it's worth, Carlton had thrown just under 3,000 innings (2986) when he was the same age as Halladay. Nolan Ryan was just under 2,700 innings at the age of 32, where Halladay is now.
Although not a Hall of Famer, former Phillie Curt Schilling had thrown 1,691 innings by age 32 or almost two seasons worth of innings less than Halladay has thrown. Early in his career, Schilling was pitching in relief, which helped to limit the innings that he had thrown. Schilling was able to pitch eight more seasons and tack 1,569 more innings onto his arm.
Of course, there are some great Hall of Famers who have thrown under the average number of innings before calling it a career. In fact, Mordecai Brown and Whitey Ford fell roughly 500 innings short of the average in their careers. Bob Lemon was almost 1,000 innings under the average and the great Sandy Koufax was nearly 1,500 innings under the average Hall of Famer in innings pitched.
Again, there are no guarantees. Halladay could have another 2,000 innings left in him or another two innings left in him. That's all part of the process that GMs go through on their way to either looking like a genius or becoming a goat, saddled with a huge contract for a pitcher who is left with too worn of an arm to anywhere near the innings that he's being paid for. All Ruben Amaro can do now is hope, trust and pray that Hallday won't become an albatross around his neck before all of Halladay's guaranteed checks have been cashed.