Wait, Zack Littell is a Starter Now?!

How in the world can you explain a team like the Rays? There are a lot of strange and seemingly magical things going on there, but let’s focus on just their starters. They churn out top-of-the-line dudes like no one’s business. Shane McClanahan is nasty. Tyler Glasnow looks unhittable at times. Jeffrey Springs went from zero to hero and stayed there. Zach Eflin is suddenly dominant. They can’t seem to take a step without tripping over a great starter.

They’re also always hungry for more. Whether it’s bad luck, adverse selection, or something about their performance training methods, the Rays stack up pitching injuries like few teams in baseball history. Of that group I named up above, only Eflin hasn’t missed significant time in 2023, and both McClanahan and Springs are out for the rest of the year. The Rays not only have all these starters, but they also traded for Aaron Civale at the deadline, and they’re still short on arms.

They did what anyone would do: point at a random reliever in the bullpen and tell him he’s now an excellent starter. Wait, that’s not what anyone else would do? Only the Rays do that? You’re right, at least a little bit; surely you recall the Drew Rasmussen experiment from 2021. That one was a big hit until Rasmussen tore his UCL this year.

But that’s not quite the same as turning Zack Littell into a starter. Rasmussen was a starter whom the Brewers had converted to a reliever due to major league necessity in 2020, and he switched back to starting not long after joining the Rays in ‘21. Littell has been a reliever for a while now. He made two starts for the Twins in 2018, then opened for the Giants twice in 2021, but other than that, he’s been a one–to-two-inning guy since making the majors.

What are the key differences between starters and relievers? I’m not talking about their workload; that’s pretty obvious. I’m talking about the traits that make you be one or the other. The things I think of are pitch diversity and stamina, and I’d wager that whatever you picked, they were some variation on those words. Can you keep hitters off balance even when they get to see you again? Can you beat opposite-handed hitters? Can you keep throwing competitive pitches even after you’ve been out there toiling for an hour or more?

That’s not a light set of requirements. Those things are hard. Plenty of pitchers have a nice fastball, and a lot of them can learn a slider that goes with it, which is part of the reason sliders are getting so popular these days. Littell fits that mold. He has a perfectly serviceable fastball — a backspinning four-seamer that he uses to dot the top of the strike zone and steal more than the occasional strike on the corners. He also throws a bullet slider that plays well off of his fastball. You’ve seen these dudes before, frequenting the seventh and eighth innings of your local major league ball club.

I have a theory that a good fastball, one that a pitcher can both command and occasionally throw past hitters, is a key part of finding a reliever who can start. Littell, and Rasmussen before him, both fill up the zone with their fastball when they’re behind in the count. They have enough movement to avoid terrible damage, too. Walks are a lot less acceptable among starters than relievers because of the length; walks just create a lot more stress, both on the starter and on the bullpen who will inevitably get stretched behind a brief start. Two walks an inning for two innings might end a starter’s day pretty quickly and leave the team scrambling to cover the shortfall. It’s much less of a big deal if your reliever gets wild and walks two guys, finishing only a third of an inning instead of his planned one.

Littell has that, but he’s missing a pitch beyond that standard-issue fastball/slider combination. Or at least, he was. In 2021, he started dabbling with a splitter. By 2022, he was throwing it 10% of the time. This year, that number has doubled to 20%. He’s also started mixing in a sweeping slider with a radically different movement profile. It’s still a work in progress — he’s only thrown 32 of them in games, so that’s hardly a surprise — but it’s another look to give hitters as he lays siege to lineups instead of trying to power through them in one burst.

The splitter and sweeper have a complementary effect. Littell’s fastball and sharp slider are both pretty good against lefties and righties alike. He’s deploying the splitter almost exclusively against lefties these days, and the sweeper almost exclusively against righties. That makes him a three-pitch pitcher regardless of who he’s facing:

There’s another benefit to having four pitches. When one of his pitches isn’t up to snuff in a given day, he can decrease its usage. When an opposing hitter is a dead-red fastball hitter or immune to chasing splitters, no worries — scrap it. That doesn’t work so well when you’re only throwing two offerings.

It might seem like I’m belaboring this point too much. Spencer Strider and Bryce Miller are succeeding in the majors with two and one pitches respectively, aren’t they? I mean, sure. They also have two of the best fastballs in baseball, period. Unicorns exist; that doesn’t mean that every horse can do whatever it wants to. I don’t think we can learn a lot about Littell’s chances as a starter by watching Strider channel Jacob deGrom for games at a time.

Okay, so we’ve got that point covered. Littell’s repertoire expanded enough that he now looks like a starter from that perspective. It’s neat that the Rays seem to be so good at teaching pitchers to throw sweepers, and also at altering their pitch mix to best take advantage of their particular skills, but they aren’t doing this with every reliever. Littell’s ready-made mix of two platoon-neutral pitches, good fastball command, and another legit secondary was a perfect fit for what they’re looking for.

That brings us to the second question: can he do it for multiple innings at a time? I’ll admit that this is a harder one to investigate from the outside. We don’t know how pitchers feel when they come off the mound after 23 pitches, or 33 pitches, or after sitting in the dugout between innings four times. The best I can do is come up with some kind of proxy, so I tried a simple one to see if there’s anything obvious about Littell that made him a candidate.

I looked at every pitch thrown by a reliever in 2022. Then, I tossed out pretty much all of them. I only wanted two numbers: the average fastball velocity for fastballs thrown between pitches 6–10 of an outing, and the average fastball velocity between pitches 21–30. In past research, I’ve found that the first few pitches of any given appearance are usually thrown below a pitcher’s maximum velocity. That makes sense to me, but it also makes looking at the first ten pitches less useful diagnostically.

In essence, what I’m looking for is guys who are already laboring by the time they get into their second inning (or first stressful inning) of work. Those pitchers are probably ill-suited to make the transition from relieving to starting; the rigors of it are likely to hurt their stuff too much. Is this a perfect measure? Most definitely not; I just can’t think of a better one that I could easily pull from data.

Bad news, though: Littell failed by this criteria! He lost roughly three-quarters of a tick as the game wore on, triple the average lost by relievers last year. By my own test, he fails. Clearly, this isn’t something the Rays are looking at when it comes to whether a reliever can start. In fact, it might not even matter at all. Littell is in the bottom five percent of relievers when it comes to lost velocity, in fact. By this metric, he’s a particularly bad candidate for this conversion.

It’s not quite as simple as that. With the foreknowledge that he’s starting, Littell has flattened out his velocity significantly. He’s losing only around a third of a mile per hour as his starts wear on, back to roughly average. He hasn’t lost a ton of velocity, either; he’s averaged 94.2 mph on his four-seamer as a reliever and 93.8 as a starter.

If the Rays are worried about extending him too far, they aren’t exactly showing it. He doesn’t have a hard stop at five innings or at 18 batters faced. He threw 82 pitches on July 30, then came back with 74 on regular rest. Now, their trust hasn’t been rewarded, exactly: batters are hitting .429/.500/.571 against him the third time through. But it’s only eight batters, and presumably if he’s this bad, they’ll adjust to that.

We’re 1,500 words into this article, and I still haven’t told you whether I think moving Littell to the rotation makes sense. To be honest, I have no idea. It’s wild to me. I still don’t quite understand how it works. I still don’t quite believe it does work. I can’t figure out why Littell is the right guy to convert instead of, say, Jalen Beeks or Shawn Armstrong. The commendable fastball and pitch mix are surely a part of it, but the Rays taught him one of those pitches this year.

All I know for sure is that I’m intrigued. I’m really excited to watch Littell’s start today. If he turns into a middle-of-the-rotation arm, or even a back-of-the-rotation arm, that’s a huge coup for Tampa Bay. It’s also a huge coup for Littell; back-end starters make a lot more money than middle relievers. Heck, Littell himself bounced from the Rangers to the Red Sox to the Rays this year alone thanks to waivers and trades for cash. Become even a below-average starter, and things look much more stable and much more lucrative.

So yeah, tune in with me! I still mostly think this will all fall apart. I can’t quite wrap my head around it. He wasn’t even a dominant reliever. The Rays can’t keep getting away with this! And yet they do, in general, so they might in this case particularly. What else can we do but wait and see the results?