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Rays Trade Target: RHP Luke Weaver

or, “What can Luke Weaver learn from Michael Wacha?”

MLB: Seattle Mariners at Arizona Diamondbacks Mark J. Rebilas-USA TODAY Sports

Earlier this week in part one of this three part series, we identified a group of pitchers with similar pitch shape to the Rays new starter Michael Wacha. That group is Brandon Bielak, Max Scherzer, Griffin Canning, Luke Weaver, Tony Gonsolin, Zach Plesac, and Lance Lynn.

In part two, we dug into the characteristics of this group, in particular their unusual rates of reverse splits, in search of processes Wacha might try out to improve his performance against same-handed hitters.

Read those first because otherwise what follows won’t make a ton of sense.

But, unless the Astros are ready to sell low on Bielak (the surely won’t), or the Angels suddenly wake up and do something weird and exciting that makes Canning expendable in their already depleted rotation, then there’s only one other pitcher on this list that could be of special interest to Rays fans. And turning the conceit from part two around, perhaps Luke Weaver has something to learn from Wacha should he become a trade target for the Rays.

Underwater Basket

Weaver had a difficult 2020 season, and he especially struggled against left-handed hitters (.405 wOBA over 24 IP) after doing very well against them in 2019 (.268 wOBA over 34 IP).

Perhaps the biggest problem for Weaver was that his fastball against left-handed hitters got crushed in 2020, to the tune of a .554 wOBA.

Luke Weaver FF vs. LHB
Data from Baseball Savant

And while this sample size is dangerously low, and there’s at least a suggestion in the xwOBA numbers that Weaver wasn’t actually hit as hard as his real-world outcomes suggested, the more stable per-pitch underlying numbers support the idea that he lost some fastball effectiveness against lefties.

Luke Weaver FF vs. LHB
Data from Baseball Savant

The fastball ended up a ball more often in 2020 and was fouled more, while being both taken for a strike and whiffed at significantly less often.

Now, Weaver’s fastball is pretty good — probably slightly better than Wacha’s 2020 version — with above average velocity and ride, and it’s been a pitch he’s been able to count on for outs over the course of his career (an excellent 20% whiff/swing rate per Brooks).

Ultimately, the most obvious process change that went wrong for Weaver in 2020 can be boiled down to “Stop throwing your fastball right down the middle.”

And we know he can. In 2019 he was able to effectively work the outside and upper edge of the zone.

Luke Weaver 2019 FF location
Brooks Baseball

While in 2020, either from being unable to get chases off the outer edge, falling behind batters and needing to throw a strike, or just a more general lack of fastball command (or any combination of the three), Weaver basically lived in the center of the zone.

Luke Weaver 2020 FF location
Brooks Baseball

But the problem is that “Stop throwing your fastball right down the middle!” is probably not actionable advice. No one wants to groove their fastball when it’s getting crushed time and time again. You get to this unhappy place out of a lack of options, and when un-slumping yourself is not easily done.

But what Weaver can learn from Wacha and the others on this list of similar pitchers is that, against lefties, he does have another option. The setup pitches for his excellent changeup don’t have to be all fastball.

His collection of pitch shapes is almost identical to Wacha’s. We know that for Wacha the cutter works up and in on the hands. But Weaver almost never throws his cutter to lefties at all.

Luke Weaver
Brooks Baseball

He can, and he should. Mixing in more inside cutter would help keep lefties off his fastball in the zone, and would likely open up the outer edge of the plate even more for both his fastball and his changeup.

In previous years Weaver has succeeded against lefties, but judging by his comps, he’s a pitcher with untapped ability against them.

Concluding Thoughts

By letting Charlie Morton and sign with Atlanta and trading Blake Snell to San Diego, the Rays chose not to try again with their World Series team, and have instead turned 2021 into a transitional year for Rays pitching.

But despite taking an immediate step back, the Boom Bands still play in Tampa Bay. This team remains in a position to contend for a championship.

It’s possible, even likely, that the Rays will boast a formidable pitching staff by the time the postseason rolls around; but it’s also possible, even likely, that there will be some kinks to work out as young players adjust to the majors and rehabbing arms return to health over the first half of the year, so the Rays should be in the market for more pitching, even with prospects like Patiño and McKay on the way.

A five year MLB veteran at only 27, who won’t reach free agency until 2024, Luke Weaver is the type of bounce back candidate with both floor and immediate upside that the Rays should be targeting to make sure they hit the ground running and stay in the mix of a competitive American League East.