Talking about the best and worst individual pitches on the team the other day got me thinking about a lot of things, most notably Brandon Morrow's fastball. The 15.5% swinging strike rate I pulled from Josh Kalk's online tool was almost unthinkably high for a heater, and I could hardly believe my eyes. So, ever the skeptic, I went searching for confirmation. I went to Matthew for help from his PITCHf/x database, and, well, bad news.
Kalk FA SwS%: 15.5%
PITCHf/x FA SwS%: 11.7%
Josh Kalk's online tool is doing something wonky, excluding some information while seemingly just making up other information, so I'd take anything you pull out of there with a grain of salt. There's something funny going on.
That said, 11.7% is still magnificently high for a fastball. Only...
Morrow FA SwS%, bullpen: 14.7%
Morrow FA SwS%, starter: 7.6%
Yikes. Morrow's fastball didn't lose much in the way of velocity upon moving to the rotation, but over a sample size of 317 pitches, it became more hittable. We'd expect that to some degree, of course, but his swinging strike rate on the fastball fell by nearly half. That's a huge, huge drop, one you wish you could write off as a sample size issue if it weren't for those damn swinging strike rates stabilizing so fast.
But now I have good news. Even though 7.6% doesn't seem that hot - especially when compared to 14.7% - the league average swinging strike rate on fastballs thrown by starters last year (minimum 500 fastballs) was 5.3%, with a standard deviation of 1.7%. So Morrow still comes out looking a good deal better than average. Even more encouraging? The list of starters between 7-8%:
Of the 168 starters last year who threw at least 500 fastballs, 20 used them to register between 7-8% swinging strikes, and the average tRA of this group was 4.14. Sabathia, Lee, and Lincecum were the three best starters in all of baseball. So even with the significant drop in SwS%, Morrow's fastball still found itself in some reasonable company.
While we don't know how Brandon Morrow is going to fare as a starting pitcher in the long run, what we do know is that his fastball gives him a pretty good head start on the road to success. Going forward, we'll see if he finds a balance somewhere in between 7.6% and 14.7%, but even if he doesn't, and he stays around where he was last September, that's still an above-average pitch at the heart of his repertoire, and that isn't to be underestimated. ~60-70% of all pitches thrown by starters are fastballs, and having such an explosive heater gives Morrow a fairly big advantage.
Brandon Morrow has a lot of developing left to do, and I don't expect 2009 to be the season in which he hits his ceiling. But there are plenty of good reasons to be excited about his potential, and if he's ever able to combine his fastball with better location of his changeup and curve, you're gonna want to be wearing rubber underpants.