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The never-changing Luke Weaver

Weaver’s pitch mix hasn’t fluctuated much this season. Good thing? Bad thing? Does it matter at all?

MLB: Pittsburgh Pirates at St. Louis Cardinals Joe Puetz-USA TODAY Sports

Everybody was excited for Luke Weaver. Fantasy baseball owners considered the universe where he was a top-20 starting pitcher. Others simply considered him a breakout. We were even excited here at VEB.

The hype was warranted. Give the changeup-heavy starter a curveball, another year under his belt and release him into the wild - nothing could possibly go wrong.

Our expectations were just a little bit off. The appropriate level of disappointment hinges on how much of an optimist you were on the former Florida State arm.

My expectations were high. I saw Weaver as a solid number-two starter behind Carlos Martinez. Early in 2018, however, I began to realize the curveball Weaver added could only help reverse his expected strikeout regression so much. A third pitch can add to a pitcher’s effectiveness simply because hitters need to consider it, even if it’s only thrown 15 percent of the time. But when there isn’t a tendency to use the pitch in two-strike counts—which Weaver has not done heavily this season with his curve—you have to question how confident the pitcher is with the offering.

Given Weaver’s extremely mediocre results with the pitch (currently a -5 value on Fangraphs pitch values/100 - not good), it’s not hard to see why he wasn’t using it when he was ahead.

The mediocrity of Weaver’s curveball likely caused its usage to fall as the season has gone on. Aside from this change, one of Weaver’s defining 2018 characteristics is how consistent his pitch mix has been.


Weaver’s poor curveball usage seems to have spurred some interest in a cutter, which I detailed in a post from a few weeks ago. This offering isn’t great either unfortunately by movement and whiff standards, but it’s been more effective than his curveball, which provides reason to favor it. Even in these fluctuations, however, we’re looking at only 5 percent changes here and there — nothing dramatic at all.

Does Weaver need to change his mix?

That’s a decision for Weaver and his pitching coach, not an analyst like myself. The reason we have pitch mix is to see how pitchers are adjusting. I consider it one of the most reliable ways to understand how a pitcher attempts to counteract struggle. It’s transparent and usually done with at least some purpose, especially if sustained over multiple outings.

Logic would suggest that something needs to change in order for Weaver to replicate last year’s success if the present variables aren’t enough. Regaining the tunneling success of his changeup from 2017 could help, but given how much of a feel pitch changeups are, correcting a tunnel point is probably easier said than done. On top of that, we can’t say with 100 percent certainty this is the reason for a doubling of the slugging percentage against his changeup.

Pitch mix alteration can also be a way to try and rely on what’s working, but this has its drawbacks as well (everything does!).

Weaver’s fastball has been a dominant this season. Hitters are slugging under .400 against the pitch and his groundball to flyball rate with the pitch sits inside the 80th percentile among right-handed pitchers. While some pitchers rely on movement to generate natural sink and create groundballs (think Aaron Sanchez, or for Cardinals relevance, John Gant), Weaver is more of a location-dependent fastball pitcher. He runs into trouble when his fastballs gets inside on right-handed or left-handed hitters, preferring to locate the pitch on the outer third as most starters do. His fastball whiffs, like so many others as well, come when he elevates. Weaver is really not too complex of a pitcher.

Could Weaver increase the usage of his best pitch? He’s throwing his fastball 56 percent of the time, down slightly from each of the prior two seasons at the major league level, but right at the league median. If Weaver were to jump to north of 60 percent again, his mix would look something like Luis Castillo’s or Kyle Hendricks’, with Hendricks the more fitting comparison given Castillo’s “Buggs Bunny” changeup and lower level of command.

Hendricks had both a cutter and curveball early in his career. His cutter disappeared after his first two seasons and his curveball is a rare offering that has only slipped further into obsolescence.

For Weaver to align himself with Hendricks, we’d need to see a fastball and changeup usage uptick, forcing Weaver to rely on his bread and butter and nothing else. The alternative is a waiting game on Weaver finding his changeup and hoping his curveball can be only mediocre as opposed to the travesty it currently is from the numbers alone.

In 2017, Weaver came with success and poor results versus right-handed hitters, something I and others assumed would be mitigated by his refined curveball. This was Weaver’s initial adjustment, but not everything stayed the same, meaning he has to adjust again.

We’re in a standoff with Weaver, waiting for his next move as he tries to fulfill the number-two starter potential we hoped and dreamed was possible.