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Kendall Graveman Could, and Should, Thrive as a Reliever

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A flamethrower, but with command!

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

As the 2020 shortened season winded down, I had a few topics rolling around in the back of my head. As someone who is strongly partial to pitching, perhaps the topic of most interest to me is what the Mariners planned on doing with Kendall Graveman. They gave him a go as a starting pitcher, but by the end of the year, he was pitching out of the bullpen due to a benign tumor in his neck. I had thought of him something like the lite version of Nathan Eovaldi, but then but his neck issues threw a wrench into things. Well, the Mariners declined option before quickly inking him to a incentive-laden one-year deal.

The details! Here are the details:

Now, I mostly posted this to show the financial details of his contract. Essentially, he’s signing for $1.25M, but by meeting a few stipulations, he could slightly exceed the option that the Mariners declined. If you look closely, though, you’ll also see that Rodriguez lists him as a relief pitcher. That’s not a typo! Graveman has confirmed his bullpen role himself.

While it’s disappointing that we’re not going to be able to witness a reclamation project of Graveman as a full-fledged starter, I can’t say it’s not going to be fun to see him reach back and throw in the upper-90s for an inning or two apiece. That’s going to be plenty of fun, and it’s probably the better fit for him anyhow.

There were several factors that played into his transition from starter to reliever. I already mentioned the tumor in his neck (which he’s said is not a problem, and he passed his physical). One thing to consider is that he may not have a repertoire suitable to go three (or even two) times through the order. Sure, he throws a hard sinker, and his cutter was sitting nearly 92 mph, but he doesn’t use his changeup much, and he doesn’t have much else in the way of a whiff pitch. Then there’s his velocity.

Here’s Graveman’s max sinker velocity, by year:

This is good! So good. Graveman reached an unprecedented level of velocity that he hadn’t yet reached in his career. That’s not to say that his average velocity was a full tick up, though.

Graveman’s average sinker velocity, by year:

Graveman seemingly increased his velocity by a touch, although the error bars are awfully wide. The issue is that he would start games throwing hard, and then pretty quickly deteriorate to the low-90s, which isn’t workable for a sinkerballer without any strong secondaries.

An example, from a game against the Houston Astros:

It’s not easy to tell from the picture alone, but you can see here that Graveman is maxing out at about 98 mph, sitting mostly around 95 mph, and eventually bottoming out below 92 mph. I don’t know how much of that could have been remedied over the offseason, but it’s obviously an issue. He already doesn’t have that many pitches to work with, but a hard sinker is an absolute must for him. In terms of pure velocity, this version of Graveman looks like a pitcher who is dominant the first time through the order, before getting pummeled the second and third time through. In the bullpen, though, this will hopefully cease to be an issue.

I took Graveman’s numbers since 2015 and put them into buckets, by velocity. For swinging-strike percentage, velocity didn’t seem to do much Graveman. When considering CSW (called strikes plus whiffs), though, elite velocity appeared to net Graveman a significant amount of called strikes, when compared to lower velocities.

A table, showing Graveman’s swinging-strike percentage and CSW, by velocity:

CSW and SwStr%, By Sinker Velocity

Velocity CSW% SwStr%
Velocity CSW% SwStr%
92-93 27.5 5.8
93-94 27 6.5
94-95 26.4 6.3
95-96 26.3 5.4
96-97 20 6
97+ 31.3 6.3

Now, the data is pretty inconclusive. There’s a huge spike in CSW at 97 mph, but that’s with the significant, significant caveat that the sample is just 32 pitches. The thing is, despite the table above, I’m not convinced that higher velocity can’t still lead to more whiffs for Graveman.

I think the issue is that he needs to be more judicious about his sinker location. Sinkers at the bottom of the zone hardly lead to whiffs, regardless of the pitcher or velocity. Sinkers at the top of the zone, though? Those can. Sinkers arm-side, off the plate? Those can too. And so that’s an adjustment I hope to see Graveman make.

Graveman’s sinker location, since 2018:

He definitely skews arm-side, in general, but Graveman keeps it low in the zone, for the most part. So where do the whiffs come from?

Graveman’s percentage whiffs on his sinker, again, since 2018:

For most pitchers, their fastballs and sinkers play best to their arm-side. This makes sense, as it’s the direction that both pitches travel. With that said, this whiff plot is absolutely shocking to me. We’re playing with relatively small samples in some areas of the zone, but Graveman gets absolutely no swings and misses when he’s pitching away, or pitching down in the zone in the middle of the plate or to his glove-side. And so, to me, it seems obvious that Graveman could use a tweak in approach to optimize his

The last development is that Graveman has purchased a Rapsodo and is working on a slider. These anecdotes come up every offseason with dozens of players, but it makes a lot of sense for Graveman. Aside from his curveball — which has historically been an average pitch for him — he doesn’t have any pitches that move glove-side with consistency. You may want to point his cutter, but the hard version of Graveman’s cutter was a pitch with arm-side movement. His mid-to-high-80s cutter was more exclusively a pitch with glove-side movement.

It’s tough to say what tweaks Graveman will make altogether, but a pitch with a lot of horizontal movement should, theoretically, help his sinker play up — it could prove symbiotic for his entire pitch ecosystem, as well.

Here’s a look at Graveman’s pitches, plotted by horizontal movement and pitch velocity:

I’ve circled in red what is likely something resembling the slider that he’ll be working on. As I mentioned before, his curveball is rather uninspiring, and so he’ll probably look to give this slider more drop or glove-side movement. For now, I can only speculate,

The reason why I love Kendall Graveman is because, in theory, he could be really great. But as it often goes, players that are good in theory aren’t always in practice. After all, there’s a reason the Mariners only guaranteed Graveman $1.25M on the year. In any case, I repeat: Graveman could, and should, thrive as a reliever, and it wouldn’t be surprising to see him be a strong backend option. I invite naysayers to kick rocks.