Addendum: I always forget to mention this, but I really love the people at FanGraphs. That site is where I get most of my information for these types of analysis, and they are just wonderful.
The whole throwing across his body thing probably isn't too good for his control or arm.After a successful season in 2007 where Perez went 15-10 with a 3.56 ERA, Perez fell to 10-7 with a 4.22 ERA despite pitching 5 more games and 17 more innings (only a little more than 3 IP/start?). I found that a little surprising when I first looked at the stats. His BABIP of .287 last season dropped to .280. His LOB% rose from 71.6 to 73.4. His GB/FB rate increased from .65 to .70. It almost seems like he should have been better. But then, I saw some other stuff. His K/9 dropped from 8.85 to 8.35, but the biggest thing was that his already high BB/9 of 4.02 went all the way up to 4.87. Perez's HR/FB also went up from 8.8% to 9.8%. In total though, he shouldn't have been much worse (at least not more than a half-run) than the previous season. However, Perez's FIP last season was actually 4.32 (4.68 this past season -- not a big jump). That was a BIG difference caused by his low BABIP and HR/FB. He's also been aided by pitching in pitcher-friendly and now extinct Shea Stadium.
What does the randomness tell us? One, he isn't a very good pitcher. The only consistency he has are his FIP's, which are always at least in the mid-4's except for his fantastic 2004 where it was 3.45 (but his BB/9 was also really below his career mark -- 3.72 vs. 4.76). Two, he's unpredictable. His high walk rate and flyball tendencies lead to inconsistency and luck playing a larger role (will the walks hurt -- LOB% -- and will the flyballs turn into outs or home runs -- HR/FB -- which may be a five foot difference). Three, he can't throw strikes. A new metric called F-Strike% (percentage of first pitches that go for strikes) is interesting. The norm is around 60-65%, but last season, Perez's was 52.9% (and usually around 55%, which is really low). If you can't get ahead, it makes it harder to get guys out. Four, he strikes out a lot of guys. His career K/9 is a really high 9.25, and teams just love power-guys who strike out a lot of people, especially lefties. Ollie is that guy, and that's why someone is likely to give him a chunk of dough this off-season. They just hope his BB/9 drops dramatically.
For those who want a Randy Johnson comparison, Johnson's first five BB/9 were 2.42 (4 games), 5.38, 4.92, 6.79, and 6.16 before dropping down to 3.49 and going down essentially ever since (How in the world did sub-4 ERA's those seasons?).
So, Perez could get his command under control (pun), but I'm not so sure he will. There is the possibility however, and I bet Boras plays that in his negotiations. Otherwise, I don't think I'd spend too much money on Perez this off-season, even if he's only 27.

















