Where has Roy Oswalt's fastball gone?

It's easy to take Roy Oswalt for granted. He's been at the top of the Astros rotation for going on ten years now, and when you put up All Star-caliber numbers with metronome-like consistency, fans can't complain about much. What's more- he doesn't talk much and has left a negligible imprint on the city of Houston because he leaves town so quickly after the season finishes. You almost get the sense that the Wizard wants to be a little mysterious, to not let any fans behind the curtain like we do some ballplayers.

While Wandy Rodriguez has been battling arbitrators,  Brett Myers, Bud Norris and Felipe Paulino have had to prepare themselves to begin their first seasons as members of the Astros' starting five. Roy Oswalt has had no adjustments to make really, besides rehabbing from a back injury which appears to be a non issue at this point. His season in 2009 didn't go quite as we've come to expect but he projects to have a solid if not spectacular season in 2010.

One aspect of Oswalt's game saw a pretty dramatic drop off last year and I wanted to figure out why. From 2005-2008, Roy's fastball was one of the strongest parts of his arsenal. After a 2005 season that saw this pitch max out at 27.8 runs better than average, a temporary decline saw a nice rebound in 2008. As I alluded to earlier though, 2009 was not a stellar year for Oswalt and the strength of his fastball was no different.

Just one run above average? This was a drop of epic proportions which didn't have an immediate answer considering how his velocity remained constant across the board. I don't know if that would have been the obvious answer but it certainly is the most popular means of explanation for diminished results from a veteran starting pitcher. Fortunately for Oswalt, this wasn't the case, but unfortunately for this me, my answer was still alluding me.

It's my understanding that "runs above average" means that the result of every fastball Roy Oswalt threw in 2009 is compared against a league wide average. Since Oswalt threw more fastballs per season than the average pitcher, the sheer volume undoubtedly helped pad his fastball value. In 2009, his fastball percentage was the lowest of his career at 60.8%. It just doesn't make much sense as to why he would just stop throwing his fastball at his 2001-2008 levels. His GB/FB ratio suffered as well last year, falling to it's lowest at any point in his career.

At this point I had more questions than answers. I barely had an idea of why Roy threw so few fastballs last season, and now I see he induced a lower percentage of ground ball as well. Could these two occurrences be related? Were they somehow involved in the Kennedy assassination? Anything was possible.

Pitch F/X data has been a revelation, allowing the most in-depth analysis of each pitch thrown in any major league baseball game. It's sort of complicated for anyone who's not all that familiar with the concepts involved, so here's a web page devoted to teaching the basics. If you're still not quite there after reading it, don't worry. I won't go that in depth.

Here are the breakdowns of Roy's 2008 and 2009 seasons. I couldn't isolate his fastballs from 2009, but the breakdowns of each pitch type are there, so at least there's that!

Again though, the similarities are striking: swings, swings and misses, foul balls and balls in play all were close percentage wise across both seasons. The aforementioned velocity difference was less than half a mile per hour. More vertical movement in 2009 is actually beneficial for a pitcher like Roy who throws a four seam fastball against like handed batters. The negligible decline in horizontal movement last season meant that his fastball ran in on right handed hitters slightly less. In general though, four seam fastballs don't have that much movement, which allows opposite handed hitters to do fairly well if presented with this pitch. It would definitely be nice to get a pitch type breakdown vs. just lefties, but I don't know if this is possible. At least I couldn't find any source with this information. Best I can do is say that in 2009 and 2008 Oswalt was generally better against left handed batters, contrary to the norm.

I'm sort of at a loss as to why Roy Oswalt didn't throw his fastball as much in 2009, and if that decrease in throwing the pitch led to a majority of it's loss in value when compared to an average pitcher. A slight change in release point, which led to hitters getting tipped off? Or maybe Oswalt lost the feel for his fastball, couldn't locate it within the strike zone, and went with other pitchers as a result. I doubt it after looking at all the information, but it's a possibility.

If nothing else, I've put some data out there, and hopefully one of you ambitious individuals can figure this enigma out. The fate of Roy's fastball hangs in the balance...sort of. Ok, not really...but please figure this out for my sake.