A few weeks ago, I wrote about the noticeable changes made to J.A. Happ's repertoire since his trade to Pirates. Just as a review, Happ has gone from a serviceable back-end starter as a Mariner, to becoming what appears to be the best trade deadline acquisition this side of Yoenis Cespedes (and potentially better than him, too).
The above data is from FanGraphs. His peripherals since joining the Pirates have been roughly in line with Corey Kluber's full season rates, with fewer home runs (although, admittedly, fewer swings-and-misses).
As I wrote last time, Happ has largely done this by throwing more four-seam fastballs, but also more hard pitches in total (four-seam fastballs, sinkers, and cutters). Per Brooks Baseball, he has thrown 88.2 percent* hard pitches since joining the Pirates, a jump from his time in Seattle.
However, the decided focus of his adjustments is the four-seam fastball, a pitch that the lefty is willing to use against batters on both sides of the plate, in any count. In fact, he's used his fastball the third-most of any qualified pitcher in the second half of 2015, and it seems possible that there's something objectively different about the pitch since his trade.
Using Pitch F/X data collected from Baseball Savant, it can be seen that this pitch added movement both horizontally and vertically, over the last two months.
The velocity is only slightly higher, but he has definitely added spin to the ball in some way. In August, Travis Sawchik described the changes made to Happ's delivery by Pirates' pitching coach, and purported miracle worker, Ray Searage, in an effort to fix his lack of consistency.
Happ... had too much rotational movement in his motion which dropped his arm slot and made the ball easier to track for opposing hitters. It also negatively impacted his control. ... "What happens is they are over-competitive and in a hurry to pitch," Searage said. "...you have to give yourself a better chance to get that release point."
Happ certainly has been better at getting that release point with the fastball since joining the Pirates, and that likely is related to his improved control numbers (data from Brooks Baseball).
Additionally, if we are to believe that these tweaked mechanics have resulted in both improved quality of pitches and improved consistency of pitches, there is also some evidence of the latter.
Above, the table shows that features of Happ's four-seam fastball (movement, spin rate, and velocity) have on average increased since joining the Pirates. The same features are also experiencing less variation from pitch-to-pitch. Performing a simple F-Test for Variance on these factors, it appears there is a statistically significantly change in the spread of each variable (and in all four cases, a smaller spread).
|Mariners - STD DEV
|Pirates - STD DEV
J.A. Happ's four-seam fastball is the pitch driving his success down the stretch with the Pirates. With the help of Ray Searage, it appears that the pitch has added life to it, and is achieving this new level more consistently.
As a 32-year old left-handed starter with elite results over the second half, Happ has become one of the more interesting free agent cases this off-season.
In the short term, he makes the potential Pirates' playoff rotation a more complicated affair. Beyond Gerrit Cole and Francisco Liriano, is Happ really a lesser option than A.J. Burnett (who has spent time on the DL, with a sinker velocity graph that looks like this), Charlie Morton, or Jeff Locke?
Even if he doesn't crack the rotation, Happ's one pitch focus might be even better suited for the bullpen. Regardless of the team's preference, he may be one of the first relief options turned to if the Wild Card Game remains close after the early innings on Wednesday, against a powerhouse Cubs' line-up and one certain pitcher.
* Note: this includes six pitches I believe were misclassified as 'sliders' instead of cutters. They feature his typical cutter velocity and drop. The slight difference in run may be due to being thrown in Colorado; there is no record of Happ throwing a slider in other starts.
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Spencer Bingol is a Featured Writer at Beyond the Box Score. You can follow him on Twitter at @SpencerBingol.