Here are two pitchers that have both pitched for the same team. Which pitcher would you rather have on your team? Since 2009 one of them has struggled but before then he was extremely productive. The other pitcher debuted in 2006 and is currently one of the best pitchers in baseball. Here are their stats:
Pitcher A (2002-2009):
K%: 18.80% BB%: 6.90% HR/FB: 9.30% GB%: 43.2%
ERA: 3.81 FIP: 3.83 xFIP: 4.00 WAR: 31.3
Pitcher B (2006-2012):
K%: 21% BB%: 6.50% HR/FB: 7.50% GB%: 33.6%
ERA: 3.19 FIP: 3.59 xFIP: 4.04 WAR: 27.4
If you haven't figured out who they are yet, you'll find out after the jump.
Player A is John Lackey while he was with the Los Angeles Angels. Player B is current Los Angeles Angels ace, Jered Weaver. It may seem surprising to some, but not long ago John Lackey was one of the best pitchers in all of baseball. From 2005-2007 there were only a handful of pitchers that could say they were better than the Angels ace. Some other pitchers that can claim they were better or were just as good include Brandon Webb, Johan Santana, and CC Sabathia.
I used FanGraphs handy filtering system on their custom leaderboards (HIGHLY recommended) and took a look at all pitchers who had a K% >= 20%, a BB% <= 8% and a FIP <= 3.40 to get a deeper look at Lackey.
[googleapps domain="docs" dir="spreadsheet/pub" query="key=0Ag3vWE1mScVDdGRENDVHRU1CZXNHQ21fT1hwU3gyd1E&output=html&widget=true" width="500" height="300" /]
His 3.34 FIP during that time is a little high for a number one pitcher, ideally you'd want it below 3.30. His 3.88 SIERA is the highest of the bunch though and that is definitely worrisome. He did do a goob job striking out batters, but his BB% was tied for last with Roger Clemens. He also did a good job limiting strikeouts, his HR/9 was one of the best in the group. Lackey also posted solid numbers in his first three seasons (2002-2005) as well as in his last two seasons and first season in Boston (2008-2010).
For some reason Lackey has really struggled in Boston though. In two seasons he's seen his SIERA spike all the way to 4.22 and 4.50. He's also seen his K% decrease the last two seasons as well. I'm not quite sure what the cause is because he hasn't lost any velocity on his fastball at (91 mph vFA) and he's a groundball pitcher. One would think that he would be fine in Boston.
I did the same thing with Weaver but I looked at his 2009-2011 seasons. The results are pretty interesting.
[googleapps domain="docs" dir="spreadsheet/pub" query="key=0Ag3vWE1mScVDdHIxYjFVQzN3Q2dEbS10dWRzQlh0clE&output=html&widget=true" width="500" height="300" /]
Jered Weaver's 3.42 FIP during his three year stretch has actually been worse than Lackey's. Weaver does have a better SIERA then Lackey, though. Weaver also has struck out more batters and has walked less, albeit it's been only .5% less. In terms of fWAR though Lackey was the more valuable one though. Lackey was worth two more wins than Weaver was.
I addressed it a little above, but again, why did Lackey start struggling so bad when he reached Boston? I looked at FanGraph's park factors to get a better idea. At Fenway both left handed and right handed batters have a bigger advantage when it comes to doubles. Other then that I couldn't find much. It's entirely possible that Lackey just started to wear down as he reached and passed age 30. That doesn't mean that will happen to Weaver though. While Lackey and Weaver aren't entirely similar to each other they do have a lot of traits that the other has. It will be interesting to see how Weaver ages, especially since he will be in Los Angeles for the foreseeable future.