For a league that has seen fastball velocity grow exponentially, it has also seen fastball percentage go down, for a simple, banal reason: fastballs aren’t as valuable as other pitches.
Look through the weighted pitch values on FanGraphs, and you’ll see that sliders and curves consistently rate about a half run per hundred pitches better than fastballs, and that has held steady even as the percentage of fastballs has decreased. This goes against the theory that off-speed was only valuable because of contrasting with a fastball; no, it’s just valuable because it’s hard to hit.
This has benefited quite a few teams. The Yankees had a FanGraphs piece devoted to them earlier in the year on how their fastball percentage dropped not only faster than the league, but also faster than expected based on their own priors. The Astros just won a World Series on that exact philosophy as well.
The Pirates, on the other hand, are a completely different story:
This in of itself isn’t a bad thing; if the analytics department and pitching coaches think that fastballs work better for them, it’s totally plausible that that’s the case. Even in this era there are still successful fastball-heavy pitchers.
For a long time, the Pirates did get the benefit of the doubt for this. Pitching coach Ray Searage has been credited with reviving a number of dead pitching careers—Francisco Liriano, Edinson Volquez, JA Happ, and AJ Burnett all benefited under his tutelage. The reasons for this made a ton of sense in that era, which boiled down to cutters, sinkers, and two-seam fastballs to induce weak, ground ball content. It’s why since the turn of the century, the Pirates rank third in ground ball percentage at 46.2%.
Yet in the era of 2016-18, the age of home runs, HR/FB% is at all-time highs. It has also been proven that fly ball hitters are better against ground ball pitchers than same trajectory batters, so the logic goes that if fly balls are, ceteris parabus, more valuable, then whiffs are probably more important than contact.
One could say to themselves, “OK, sure, that all may be true, but what if this just works better for their pitchers? They just might be ground ball pitchers.” My rebuttal would be: Gerrit Cole and Charlie Morton.
Morton, as has been covered, got significantly better after moving from Pittsburgh to Houston. Part of it is, yes, all of his pitches got significantly better and he added spin, but his curve whiff rate, for example, was the same in 2015 (Pirates) and 2017 (Astros). The difference was that he threw it about six percent more, and made his fastball merely one great weapon among many.
The same could be said for Cole. His spin rate jumped considerably, so point to the Astros for cracking that nut, but despite the fact his slider/curve whiff rate is similar or lower than before...
...he’s still throwing much, much more:
Which brings us to Pirates pitchers who are still rostered. Jameson Taillon, for example, has similar talent to, say, Cole or Morton, but his 102 ERA- leaves a bit to be desired. Let’s say that we want to hack Taillon to more success. Well, let’s look at it like an Astro, or a Yankee, or any team seeing the obvious trends we’re seeing.
Right now, Taillon is following the fastball-first approach, with some recent adjustments:
On a completely unrelated note (sarcasm, obviously), here is how his whiff rates on each pitch category are headed over time:
I’ll spare you the charts, but the same could be said for the rest of the staff. Ivan Nova’s lowest slugging against and second-highest whiff rate comes from the curve, but he has decreased his fastball usage in favor of the fastball/sinker combo. Trevor Williams consistently uses a fastball-first repertoire, but his highest whiff rate consistently is with his slider. Chad Kuhl, even, has a hard change/slider combo he uses only about 30% of the time despite the fact that—shocker—his slider has the highest whiff rate of any of his pitches.
For all we know, the era changes and this becomes more favorable strategy. But I just don’t see it. Fly balls are more valuable on a per 100 basis then ever, and it has almost been proven today that breaking pitches are more valuable than fastballs, and accentuate the value of even-faster-fastballs. Multiple Pirates pitchers have now moved on to more slider/curve-heavy environments and thrived. All of the neon signs are right there, and the Pirates just need to see them.