STATE COLLEGE, Pa. -- The Pirates have reached the traditional "halfway point" by virtue of the All-Star break on our baseball calendar, even though the club technically arrived at that point a few games ago.
No matter. Now is as good a time as any to take stock of the club's arms over the "first half" from a sabermetric point of view. Today, let's focus on something that wasn't supposed to be present as, well, something to focus on. Here, we'll chop it up in a few digestible chunks, picking out some trends and nuggets along the way.
Before the season even began, the 2019 version of Pirates pitching was thought to be built around the breaking ball. When Jameson Taillon started throwing a slider in May 2018, it was meant to usher in a new era in which Pirates pitching was to be freed from the shackles of pitch to contact brought about by a fastball heavy diet.
Don't get it twisted: the Pirates are still beholden to the heat. But this year's model has embraced the right kind of heater.
First, the facts: Pirates hurlers -- both relievers and starters -- throw fastballs at a 59.1 percent rate, good for the most in MLB by percentage. If we were to chop that up a bit further, we would see that Pirates starters throw them at a 56.3 percent clip, fourth most in baseball. Pittsburgh relievers are at 62.5 percent, the single highest figure among all of baseball's relief units, 0.2 percentage points higher than the Dodgers, the second-highest heat hurlers.
Here's where things take a turn. Pirates pitchers are throwing fewer two-seam/sinking fastballs at just 14.4 percent, down from 20.4 percent in 2018. No, it is the four-seam fastball that the Pirates have leaned into, at least in terms of fastballs. The team's usage of the heat is up by 5.6 percentage points, up to 46.8 percent.
A quick look across those that have amassed at least 100 four-seam fastballs thrown in 2019 provides deeper insights:
Here we can see our habitual four-seam users, coupled with their contact quality figures and their Fielding Independent Pitching marks on at-bats decided by that pitch. Though the figures might leave a little to be desired, they take on a better shine when noting that the current league rates for xwOBA and Average Exit Velocity are .358 and 89.9 mph, respectively.
In that light, many Pirates pitchers should be applauded for their ability to get the most out of the ol' tried-and-true.
Or, do they?
The FIP figures up there are a bit misleading. I pulled the cumulative four-seam data for all of these pitchers shown. Of all of their four-seam fastballs thrown, 78 percent were paired with a breaking ball on the very next pitch. 45.5 percent of the at-bats that compile that 78 percent carried vertical location changes of 9.5 inches or more. Among those 78 percent, Pirates pitching has collected a much more attractive .287 xwOBA on those breaking balls that come as the second pitch of the pair. The MLB rate under these exact parameters is .304.
So, in plain English: Pirates pitchers use their four-seam fastballs a bit differently than most clubs. MLB pairs a four-seam fastball with a breaking ball at a 70.4 percent clip. While not a complete drop off, this is a substantial difference.
In this way, the Pirates are not necessarily relying on the four-seamer to do all the heavy lifting in inducing whiffs, even if the proceedings actually end up going that way. At this moment, MLB hurlers see 30.9 percent of their combined whiffs coming from a four-seamer, while the Pirates see 36.5 percent of their whiffs coming from the straight heat.
To be sure, some are helping to push the curve toward this figure. Felipe Vazquez, Richard Rodriguez and Michael Feliz come to mind, who simply compile more whiffs on the heat simply from quality and volume. But then again, we see this phenomenon occur in Trevor Williams, who sees 81 of his 124 total whiffs coming from his four-seamer. That's a 65.3 percent rate, second only to Rodriguez.
While the four-seam fastball clearly does not tell the entire Pirates pitching story over the first half, it is certainly a fascinating wrinkle to keep an eye on.
MORE MOUND VISIT
July 5: Dickerson feasts on fastballs
July 3: Dinger Data: Bell Blasts
July 2: The Four-Seamer awards
July 1: Forget BABIP
