Foul balls are typically a successful result for a pitcher. In a no-strike or one-strike count, they are as good as a whiff or a called strike. In a two-strike situation, of course, they are generally useless, but they do little harm, keeping the count the same. Yet foul balls are difficult to credit: does a pitcher deserve lauding for earning a bit of poor contact, or skepticism for failing to miss the bat entirely? For Logan Gilbert, and Logan Gilbert’s four-seam fastball in particular, the answer to that question may be an important one, or it could be something he could improve enough to avoid altogether.
The debut campaign for the Seattle Mariners slender young fireballer was ultimately a success, as he put up a 4.68/3.73/4.49 ERA/FIP/DRA in 119.1 IP. He took his lumps at times, but did enough to show himself to be perhaps Seattle’s most imposing arm. El Flaco, as some Latin teammates call him, or LoGi Bert (in the French pronunciation like “bear”) as currently only I call him had a fairly common rookie repertoire: loads of fastballs, some trepidation utilizing the off-speed pitches, sticking with what’s comfortable to avoid falling behind in counts. And for the most part, that was enough for Gilbert to get by. He took sign number one 61.5% of the time, one of the highest rates of any starting pitcher in MLB and got fabulous results. Baseball Savant calibrates “Run Value” based on the results of each pitch based on expected outcomes, obviously giving credit to pitchers for reducing the number of runs while punishing them for increasing that number. The more negative the number the better, and in terms of total opponent runs prevented, Gilbert’s fastball was among the best four-seam fastballs in baseball.
So we’re good, right? Here’s a 6’6 Floridian baseball prodigy from the school that produced Jacob deGrom and Corey Kluber, start building the trophy case. But a few things are amiss. First and most obviously, cumulative stats say something different than rate ones. Almost nobody threw more four-seamers than Logan Gilbert, he’d better be getting some good results on them or else he wouldn’t be pitching much longer. But as the numbers further right on the chart above show, Gilbert isn’t quite matching his top-tier contemporaries in domination with his heater. A 21.6% whiff per swing (and a 12.2% swinging strike per pitch) rate is respectable on a fastball, but it’s more average than elite, a disappointing reality given Gilbert’s 95.3 mph average fastball is well above-average for velocity, particularly for a starting pitcher, right in line with aces and top talents like Walker Buehler, Shohei Ohtani, Robbie Ray, and Germán Márquez.
The other cause for concern on Gilbert’s heater is that it did get somewhat battered on occasion. The traits of his heater are good, given his length and league-leading extension combined with velocity, yet he gave up a decent amount of hard contact and didn’t always miss bats when the barrel didn’t align. What gives? I have a hunch, and it rhymes with vocation.
Hoo boy that’s a lot of the heart of the plate. Though the much lauded curveball was inconsistent, Gilbert actually located his slider rather well at or just below the zone most often. Not only that, but while his changeup was fairly erratic vertically, it typically ended up just off the outer half. The heater, however, set up a brick and mortar business and became a neighborhood institution right down Main Street. Every coach from the age that pitching becomes a skill instead of a prayer to get near the plate will tell you throwing fastballs where Logan Gilbert did all year is a recipe for disaster, and instead it just went pretty well. In fact, by Baseball Savant’s swing/take metrics, Gilbert was comfortably above-average overall in the heart of the plate, likely a credit to his stuff. It’s also perhaps a realm for improvement.
The reason Gilbert got decent results last year was, among other things, that he induced gobs of foul balls. Working off the Pitch Leaderboard from Alex Chamberlain, Gilbert had the fourth-highest foul ball rate on his four-seam of any starter who threw at least 600 four-seamers. 26.5% of his heaters ended up as souvenirs for someone along a baseline. A lot of Gilbert’s pitches this year looked like this.
You get the idea, and it’s not an unworkable route to success. As Michael Ajeto recently wrote on Robbie Ray, learning to trust your bat-missing stuff and just pump the dang zone works if your stuff is good enough. But Gilbert’s secondaries are, at least as of yet, not Ray’s caliber, nor does he have the reigning Cy Young winner’s gift of southpawedness. Still, inducing foul balls is a perhaps under-appreciated skill. Leaning once again on Alex Chamberlain with some work he did for FanGraphs, we have reason to believe that four-seamers that induce lots of foul balls are ultimately beneficial pitches towards a pitcher’s strikeout rate and, by proxy, their overall effectiveness. What ain’t broke don’t need fixin’, eh?
And yet, I come back to a final wariness for Gilbert and his profile. He can likely carve out a solid career living over the plate’s heart as he did in his debut, but he is likely leaving meat on the proverbial strikeout bone.
Consider one final chart, this time from Jeff Zimmerman over at FanGraphs. The chart below measures swinging strike rate out of total pitches for all four-seam fastballs from 2015-19, broken down by velocity as well as vertical height in feet off the ground.
Zimmerman notes that 2.5 feet off the ground is roughly average middle of the zone, with a foot higher or lower the general edges of it, though that varies hitter to hitter. It’s glaringly evident that four-seamers are more effective in luring whiffs the faster they’re thrown, but more important is that they be elevated in the upper third of the strike zone or just above it. Low four-seamers or those in the middle of the plate are at far greater risk of contact, and even if Gilbert has a preternatural knack for getting some extra foul balls, contact can be treacherous. Instead, hopefully 2022 features more fastballs in the upper third of the zone like this gem.
I suspect living just a bit higher is possible for Gilbert as he settles in with a few initial nerves behind him, less amped for every start and more able to execute with the collectedness that signified his minor league dominance. Much of what makes up an excellent big league pitcher is already present in Gilbert, but the slightest tilt upward in targets could send his performance skyrocketing.