Saber Bombs are MLB FanHouse's introduction to sabermetrics, those new and sometimes unwieldy metrics that are changing the way we think about baseballIf you're even a semi-ardent baseball fan, chances are good that you've seen MLB.com's new Gameday feature this year, which gives an incredible and detailed synopsis of the action on the field. The most interesting byproduct of the new Gameday is that Pitch FX data is now available to the general public for every pitch throw. If you're unfamiliar, Pitch FX measures the speed of each pitch in two places (at the release point and as it crosses the plate), as well as horizontal and vertical break. Many people see this wealth of information as the next frontier of sabermetrics, because it allows more detailed analysis than ever of each pitcher's start.
Earlier today, Brinson already told you about Nick Piecoro using Pitch FX to analyze Brandon Webb's "dead arm." Spurred on by that and Bob Melvin's claim of Randy Johnson's fastball being fine, despite radar gun reports, I decided to dig into Dan Brooks' Pitch FX tool to see if Melvin was right about the Unit. Follow along after the jump, and I'll show you how I answered the question.
I've been using Dan Brooks' Pitch FX tool to dig up data on pitchers. All you need to know is the day of the game and the pitcher's name and you've got everything at your fingertips. This question is a fairly simplistic one, but you can see from the log of Johnson's game on Saturday that Brooks' site generates charts that tell you just about everything you need to know about the start. The question, though, is fastball velocity. The gun on the scoreboard said 87-88, while Melvin said he was averaging 91 and hitting 94.
The green dots are fastballs, though using some of the other charts, I'd guess that only the ones showing up on the top right of this graph are four-seamers, which is the pitch in question (Pitch FX is not perfect with typing pitches). You can see that most of Johnson's fastballs were above 88 mph and probably half of them were over 90 mph. If we grab the raw data out of Dan's site and run the numbers on it, we get an average fastball speed of 90.4 mph (right in line with his average for the season) with a top speed of 92.7 mph on the start. That's pretty much in line with Melvin's claims, even if Johnson did dip down to around 88 or 89 several times during the game. He's clearly not the Big Unit of old, but you don't need Pitch FX to tell you that.
