A few reasons why Tyler Wells has become so homer-prone

On June 15, Tyler Wells threw 6.2 strong innings against the Blue Jays, his only runs allowed both on solo homers. This past outing against Tampa Bay was marred by an uncharacteristically messy four-run second, but otherwise Wells was true to form: he served up two more solo jacks.

In fact, of 31 earned runs Wells has allowed this season, more than three-quarters (24) have been on home runs. This trend is puzzling for at least two obvious reasons.

One, home runs are about the only thing Wells is doing badly at this year. Even after last night’s loss, he’s still 6-3 with a 3.22 ERA, and 88 strikeouts in 86.2 innings (a 69^th percentile K%). Wells also has a brilliant MLB-leading 0.89 WHIP. He’s the Orioles’ most valuable starter by a long shot and has contributed more team WAR than Adley Rutschman. So all in all, a huge year for him thus far.

Two, next to other MLB pitchers who give up home runs, Wells is the only one who’s not also allowing lots of hits and hard contact. Only Jordan Lyles, Lance Lynn, JP Sears and Yusei Kikuchi have HR/9 rates exceeding Wells’ 1.87 per game, and each of these pitchers allows about a third more walks and hits than Wells does (each has a 1.26 WHIP 26 or above). Wells has allowed wimpy contact for the most part: this year opposing hitters’ average against him is .184, the lowest in MLB after Shohei Ohtani.

A pitcher with a low ERA who strikes out lots of hitters, gives up few hits, and yet is prone to the long ball. It is, in fact, as odd as it seems.

What to make of this pattern? Here are some explanations, and some thoughts on whether they hold water.

One explanation: it’s the ball.

Just want to mention this one. It goes like this: Wells isn’t giving up more fly balls this season (his 2023 rate is just below his 45.3% career average), but for some reason the ones he’s allowing are more likely to leave the yard. While only 12% of his fly balls in 2021-22 resulted in home runs, this year 16.7% are exiting the park. Coincidence much?

There’s mild evidence of continued, or different, juicing this season and elevated home runs, but so far it’s hard to say it’s significant.

But the bigger problem with this explanation, in Wells’ case, is that some of the contact he’s allowing is, indeed, hard. His average exit velocity is up 1 mph this season, and up 2 mph on fly balls specifically (90 mph, vs. the MLB average of 88.1). He’s allowing a career-high 11.2% barrels, compared to an MLB average of 8.7% (barrels are batted balls hit over 98 mph with a 26-30-degree launch angle—i.e they are the stuff home runs are made of). A career high for Wells, this barrel rate is in the 18^th percentile over all pitchers.

Now, if you combine Wells’ stinginess with hits/walks (a 1st-percentile WHIP) with an exit velocity that’s average (in the 46th-percentile), what you might take away is this: most of the time, the contact is soft, but occasionally it’s really hard (especially on fly balls, which, for Wells, are frequent—around 45% of batted balls vs. the MLB average of 33.9%). Often, batters are getting under his pitches (resulting in pop-ups and weak flyouts), but sometimes they square it up, and that’s dangerous.

In short, we don’t really need a baseball-shaped explanation for all the long balls. Next!

Another explanation: it’s his delivery.

Standing 6’8”, Wells has one of the highest release points in the game due to his height and his almost overhand delivery. Does that make him easier to read out of the hand?

Answer: it shouldn’t. With an average release point of 6.9 feet off the ground, Wells, if anything, should be harder to pick up than a more diminutive pitcher like Atlanta’s Spencer Strider. But Strider excels in release extension for his height, and Wells doesn’t. There is Statcast evidence, however, that Wells has adopted even more of an overhand throwing angle (here you can check Wells’ average release extension and horizontal/vertical release for all of his pitches). These mechanical adjustments can be seen, perhaps, in a four-seamer that went from a massive liability in 2022 to a strong asset in 2023.

Whether that’s to do with making maximum use of his height or something to do with spin, either way, if anything, Wells should be harder to pick up this year, not easier.

Another: he attacks hitters/throws strikes.

There might be something to this argument. Wells doesn’t necessarily throw more strikes than other pitchers (at 64.9% vs. an MLB average of 65.3%). But this low-ish strike percentage may reflect how many strike-to-ball breaking pitches Wells throws, plus those high fastballs he loves. Given that he does have above-average whiff rates and CSW (called strikes + whiffs) percentage, it might be fair to conclude that Wells is adopting an aggressive approach of attacking hitters (and succeeding at missing bats).

Stuff: he’s not a hard thrower.

So this one is true, and clearly velocity matters. Wells’ fastball clocks in in the 17^th percentile, at a not-terribly-impressive 92.5 mph. We know that pitchers can get more homer-happy when they start to lose velocity (e.g. Lance Lynn).

But Wells never was a hard thrower, and where he excels is spin: his stuff has greater than average spin and vertical drop, which makes it more deceptive than its velocity indicates.

One way to check the relationship between Wells’ spin and home runs is with game day results. This graph charts Wells’ RPM across starts. For each home run he’s thrown this year, I went back and looked to see if reduced spin could explain it. The dates of Wells’ home runs are: April 9, 14 and 26, May 2, 7, 18 and 24, and June 4, 15 and 21.

Tentatively, I’d say there may be a correlation. For instance, on April 9, against the Yankees, his fastball spin was randomly quite low. That day, he served up long balls on heaters to Aaron Judge and Franchy Cordero. The location on the Judge pitch, incidentally, wasn’t bad: on the corner. But Judge is Judge, or Wells’ fastball just wasn’t as sharp. Either way.

On June 5, Wells had a bad changeup, and that was the pitch SF’s Blake Sabol served into the stands.

On May 2, Wells’ slider and changeup weren’t spinning well, and Bobby Witt Jr and MJ Melendez clobbered one of each in Kansas City in the first inning that day. (Another trend of Wells’: the home runs tend to come early—eight of his 18 were in the first or second innings. Not infrequently, they also come in bunches, like on that day in KC.)

Also, for whatever reason, his cutter spin rate has been declining all season. I have no idea why this is, but it’s true that the pitch is becoming kind of a weakness of late: since May 18, half of Wells’ home runs allowed have come on the cutter.

There’s a particular pitch/zone he gets hit hard on

This is tougher to sustain, because Wells has allowed home runs off his fastball, changeup and his cutter at pretty significant rates. Still, none has been a bad pitch: hitters are averaging just .178 off the fastball and are whiffing at a 21% clip off the cutter.

One thing that can be said of Wells’ home runs is that location matters. A great majority of these shots came off pitches that leaked into the upper-third or the middle of the zone. Here, I think is where spin and velocity matter: Wells doesn’t have the heat to overpower batters when he misses. And on days where he doesn’t have great spin, the location tends to waver, making the pitch hittable.

It’ll be interesting to see how this trend evolves over the season, but in my view, despite Wells’ subpar most recent outings, we shouldn’t worry about him. So long as the big right-hander keeps limiting traffic on the basepaths, his propensity to give up home runs will remain a quirk and not a real problem.