To expand on the concept above: I ran a relatively quick study to explore and support how many innings and how much performance can be expected to be lost each year into a multi-year contract. I started by viewing the 2003 pitching leaderboards from six seasons ago, as a five year contract is what C.C. Sabathia was offered by the Brewers, and therefore the timeframe most relevant to this discussion. I selected every player to have thrown over 200 innings that year to be my initial sample. In order to eliminate factors that could have a negative effect on the accuracy of the study, such as player retirement or more extreme talent loss as a player approaches the age of 40, I threw out all pitchers aged 30 years or older. This left 25 pitchers as my final sample, with ages ranging between 22 and 29 and their average age about one year younger than Sabathia's 28. The following is a table of the average number of innings pitched during each season of the 25 pitcher sample. 2003 2004 2005 2006 2007 2008 ----- ----- ----- ----- ----- ----- Innings 216.3 185.5 172.0 142.5 125.1 127.5 % Change -14.3 -7.3 -17.1 -12.2 1.9 Geometric Average % Change per Season = -10.04% This result falls in line quite well with other studies I have read on the subject, and the expected loss of 10.04% of innings each season is incredibly close to the generally accepted 10% loss that is often used by baseball statisticians. I also looked at the number of games started each season by my sample of pitchers. Below is the data table. 2003 2004 2005 2006 2007 2008 ---- ---- ---- ---- ---- ---- Starts 33.0 29.2 27.1 23.0 19.8 20.4 Change -3.8 -2.1 -4.1 -3.2 0.6 Average Change per Season = -2.5 This sample so far has shown that a pitcher's expected number of innings per season should be lowered 9.8% each year and their expected number of starts should be lowered by 2.5. These numbers fit together, as a 9.8% reduction of 200 innings pitched is a reduction of 16 innings, approximately 2.5 starts given an average start is about 6 innings. http://i35.photobucket.com/albums/d175/sbrylski06/pic1-1.png While I had the data at hand, I also looked at expected changes in K/9, BB/9, HR/9 and finally ERA. Below are the graphed results. http://i35.photobucket.com/albums/d175/sbrylski06/pic2.png The sample's K/9 rates decreased by 0.127 per season, while their BB/9 rate increased by 0.019 per season. So not only must a club be weary of handing out a lengthy contract to a pitcher in fear of injury and reduced workloads, decreases in performance should be expected as well. Not that its surprising, though. Notice the high level of fluctuation in the HR/9 graph. Partly due to using a modest size sample, but it also is merely an illustration of how much home run rates can vary for pitchers year to year, as home runs are a much less frequent occurrence relative to strikeouts and walks. The HR/9 rates for this sample increased by 0.005 per season. Plug the above three average change in rates into a fielder independent ERA formula, I will use FIP, and we can see the expected change in results from year one to year six. FIP = (13*HR + 3*BB - 2*K) / IP 1st Season FIP = 3.99 6th Season FIP = 4.21 That's a loss of .22 points of ERA due to diminished skills. If we look at the actual data, the pitchers lost about .1 points of ERA per season, which is even more significant. 2003 2004 2005 2006 2007 2008 ---- ---- ---- ---- ---- ---- ERA 3.82 4.06 4.03 4.67 4.26 4.29 Change -.24 .03 -.64 .41 -.04 The difference between the FIP estimates and the actual data is likely due in part to the modest size sample, but could also suggest and support that the pitchers are losing other skills each season, such as the capability to suppress their BABIP below league average.