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Crafting a Gameplan for the Rockies Bullpen, Pt. 3: Gavin Hollowell

Welcome back the “Crafting a gameplan” series, a in-depth and data-based look at the Colorado Rockies pitching staff. In this edition, we’ll be taking a look at the Rockies bullpen.

This is Pt. 3 of a six-part mini-series about the Rockies bullpen integrated within the ‘Crafting a Gameplan’ series. I will discuss the Rockies bullpen as entity, and I will be covering each pitcher in the ‘pen (as of the time of writing) individually at one point or another, but will group athletes who share similarities in pieces so each one has a particular theme. I will eventually dedicate a full piece of the series to take a look at possible free agent options, and the final article will be a recap. The intended structure of this mini-series is as follows:

Each new entry will feature links to the previous parts, displayed up above. You can find the previous entries of the ‘Crafting a Gameplan’ series here:

Thank you very much for reading.

In our previous entry, we tackled Justin Lawrence and Jake Bird, two of the four righties we wanted to do a deeper dive on, and today we wrap up the right-handers with Gavin Hollowell, a pitcher with very limited MLB experience but significant tools.

Gavin Hollowell

Of all the rookies the Rockies saw in 2022, Hollowell was the youngest. The right-hander, who made a few appearances towards the very end of the season, turned 25 just recently and showed impressive skill in his brief big-league cameo. Like with Lawrence, the final numbers weren’t pretty (six earned runs in seven innings), but also like Lawrence, there’s a lot going on beneath the results. Here you can see his mechanics:


Plus sweeping slider

Like Lawrence, Hollowell throws a really good sweeper in the 80-82 MPH range, and batters were almost totally hopeless against it in the few MLB innings he tossed, whiffing a third of the time when taking a cut and generating nothing but lazy pop-ups when they made contact. Hollowell’s feel for it is quite good, and this is going to be a terrific weapon when facing righties. Sweepers are well known for being dominant hand-on-hand, and Hollowell’s is no ordinary sweeper; he routinely pushes 15 inches of sweep on this pitch, similar to Justin Lawrence. Another plus for this slider right-on-right is that, because of Gavin’s sidearm slot, it creates very extreme horizontal angles on right-handers (think of Chris Sale against lefties, though not as extreme).

Elite extension

If you remember back to the chart I had in the first part of this series, Hollowell was the only Rockies reliever, aside from newcomer Brent Suter, with truly elite extension. This means that even though his raw velocity is average at best, and possibly a bit below average, his ability to get down the mound makes up for it, putting his perceived fastball velo in the 94-96 MPH range and going from possible weakness to a trait that can be considered neutral or good when you consider his low release point.

Different release point

On that release point: Hollowell is tall (6’7”) and has long levers, but his natural arm slot is that of a sidearmer, putting his release point at around the same height as Jake Bird’s. We’ve already explained how this helps his slider and as always, unique relase points are a bonus for us. We can create flatter vertical approach angles (VAA) than usual, and that’s not just for our four-seamer or slider.

Fastball utility

When he threw a few cutters in his last outing of the season at LA, Hollowell completed the trinity of fastballs: a sinker, a cutter and a four-seamer. And while none of them stand out in theory as dominant offerings, the fact that he has all three gives him terrific utility to attack all kinds of hitters. We can throw the four-seamer up in the zone against steep swings and take advantage of our good VAA, we can run sinkers in on the hands of righties, we can throw cutters to bridge the gap between our fastballs and our slider and get soft contact up and in versus lefties. We have three different weapons to use, and all we have to do is figure out how to deploy them.

Good control

A frequent issue some young relievers have is problems with walks, but Hollowell doesn’t fall into that category. He walked just 2.6 batters per nine innings in three minor league seasons and showed no issues throwing the ball in the zone at the major league level during his brief cameo. He didn’t draw many chases, but A) the sample was very small, and B) his cutter didn’t appear until the very end of his season. We’ll see how this evolves moving forward, but I have no concerns about wildness costing him dearly.

Hollowell doesn’t have the single plus (in my estimation) fastball that someone like Bird has, but he has excellent fastball utility, good control and solid velo to pair with his plus sweeper, which is a great foundation for a reliever. Now, for the weaknesses.


His fastballs are mainly situational pitches

As I said before, none of Gavin’s fastballs are truly dominant pitches in a vacuum, and their success is likely to depend on being used in the right matchups. This means more gameplans to execute, of course. What if he can’t really find his feel for his sinker one day? You never know.

Unclear changeup feel

This is something I wanted to put here just because it’s an uncertainty at the major league level. Hollowell threw just three changeups in his brief big league cameo, so I have no reliable detailed spin data, but the few he threw had pretty exceptional armside run. Look at this one that starts inside and off the plate against Gavin Lux, enough that he gives up on it, only to move like a screwball and catch the inside corner. Again, this is not me calling Gavin’s changeup bad in the slightest, but I wanted to point out that it hasn’t been a factor so far (though it probably will be soon). And because of the rest of his pitch mix (three average fastballs, a plus sweeper), a working changeup is important for him to deal with lefties.

And that’s it for his weaknesses, in my opinion. Hollowell does a lot of things well, has a lot of weapons that make up a good and cohesive pitch mix, and he’s always shown good ability to throw strikes. Let’s see what our gameplan is.


Our main challenge here is figuring out, via proper scouting, which hitters we should be attacking with each fastball. The general idea looks something like this:

Sinkers vs RHH and flat swing paths

As his sinker is more of a running two-seam type, we should expect larger platoon splits on it than on Bird’s bowling ball sinker, for example. This means its use should generally be limited to righties and lefties who tend to hit the ball on the ground, and we would be heavily sinker-slider dominant when facing right-handers.

Four-seamers up vs steep, uphill swings

Neither the velo (95ish) nor the shape of Hollowell’s four-seamer are plus, but thanks to his release point, his VAA when throwing up in the zone most certainly is. This means we can take advantage of batters who can be beaten upstairs, including in two-strike counts. The high fastball is not an auto-win button, but it’s an excellent weapon to pair with our sinker. And again: keep the four-seamer usage situational. Just because the VAA is flat doesn’t mean we should rely too much on it.

Cutters to the glove side

The cutter Hollowell started throwing has a good amount of potential. Not only does it serve as a middle ground between fastball and slider, it can be a powerful weapon up and in to lefties, as we went over already with Bird and Lawrence, particularly because of the flatter VAA and more horizontal action it has. For some reference, right-on-left cutters thrown at least at 2.75 feet of height and to the glove side of the plate have produced a .301 wOBA against over the past two seasons. In other words, this is where you want to go R-on-L with a cutter, especially if it doesn’t have tons of depth (as is the case with Hollowell’s right now):

Baseball Savant
Keep throwing the hell out of that slider

It’s a great pitch, and Hollowell already throws it a lot (40% of the time in his first taste of MLB action), but I wanted to reinforce this idea. Just because we have good fastball utility doesn’t mean we should be throwing 60% fastballs, or even 50% fastballs. As we said before, that slider is a fantastic weapon against right-handers, and you can even get some called strikes with it against lefties if you mix it up well enough, because Hollowell has good feel for it.

There isn’t much else to be said: his slider is great, his changeup can be a weapon versus lefties and his fastball utility is good. We’re looking at a sinker-slider-cutter pitcher against right-handers and a cutter-slider-changeup pitcher against left-handers, with the four-seamer there when needed to get above a barrel up in the zone. Like Bird, Hollowell is a well-rounded reliever with clear talent for spin. I believe he’ll be a crucial part of the bullpen moving forward.

The Conclusion

Like Lawrence and Bird, Hollowell has a number of excellent traits that point to future success: a plus slider, a release point that differs from average, great fastball utility and an ability to create movement on his changeup. Another thing to like with him is that he’s never had issues throwing strikes throughout the minors, with his walk rates being consistently above average. He’s a great potential example on the importance of fastball utility, and a good test for the Rockies’ pitch calling tendencies, which have not been optimized like many other teams. When you have a reliever with five different pitches, establishing defined pitch mixes and plans of attack based on the batter at the plate should be a priority, because you have the luxury of a variety of weapons. There is no reason for Hollowell to throw almost any sinkers against lefties, or changeups against righties.

It’s not clear whether Hollowell will be a part of the MLB bullpen right away or if he’ll spend some time in Albuquerque, but based on his skill level and arsenal, I’d be very surprised if the former scenario doesn’t happen. He’s one of my picks to really stabilize the back end of the Rockies bullpen, and I’m excited to watch him pitch. Remember, tomorrow we’ll go over Lucas Gilbreath and Brent Suter!

(Chad Smith was going to be next on the piece, but the Rockies traded him to the Oakland Athletics not even 24 hours ago, hence why this entry is shorter than usual)

This is a study made through my own research and conclusions. In order for it to be truly complete, it would require things such a biomechanical breakdown and some feedback from the pitcher himself, among others, which is data I don’t have access to. Please take what I present more as a suggestion than a stone-cold fact.

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