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BYB 2021 Tigers Prospect #28: Zack Hess has plenty of upside in relief

With two really good pitches, Hess could move quickly as a bullpen asset

Jay Markle/Bless You Boys

Zack Hess had to wait until the seventh round of the 2019 MLB Draft to hear his named called. The right-hander out of LSU had a ton of talent, but he also had a very high effort and funky delivery that scared teams away. The Detroit Tigers selected him with a plan to transition him into a relief arm, and potentially a very good one.

Fast forward to present day. Hess has logged 22 appearances as a reliever, he spent a few weeks at the end of last season at the alternate site, and now he’s a non-roster invite to Spring Training. We’ll get a chance to see what his time at the alternate site did to help him during Spring Training.


During his time at LSU, Hess showed off his swing and miss stuff without issuing too many walks. As a known quantity on the prep circuit, Hess was viewed as potentially fast moving relief prospect, but chose college instead. There he remained a starter, but the results weren’t particularly good. Still, his big fastball and potential wipeout slider made him an intriguing relief pitching prospect and things have come full circle for him in pro ball.

After the Tigers selected Hess in 2019 he appeared at three different levels of the minors, but spent the bulk of his time West Michigan in the Midwest League. There was good parts, including a 2.57 ERA and 9.43 K/9 in 21 innings of full season A ball. Unfortunately there was bad too, like a 4.71 BB/9.

Hess has two potential plus pitches in his fastball and slider, which means he could have a very bright future at the backend of a future Detroit bullpen. However, as with any prospect, he needs to put everything together to reach those heights.


Pure stuff. That is the big strength here. His fastball and slider are both legitimate swing and miss pitches which he can utilize in any situation.

At its highest, his fastball topped out at 97 MPH during his pro debut. More often than not he was sitting in the 93-95 range. The pitch gets some armside run, but it’s true power comes from the riding life it gets up in the zone. When he can spot it up there it becomes difficult for hitters to square it up, and that’s if they even make contact with at all.

Hess also shows a slider that’s anywhere from 83-87 MPH and can show some really late bite. He’s also not shy about using it in any count, regardless of if he’s ahead or behind. It’s a strikeout pitch, but he can use it early on to steal a strike as well. It plays well down in the zone and can really be an issue when he sets the eye level up high with fastballs before snapping off a slider that breaks below the zone.

Beyond stuff, there are some interesting notes in his delivery. It’s weird enough to be a little deceptive and Hess keeps his body closed to the target until release, when he quickly snaps on target at release. As a result, he hides the ball well, and combines that with a very quick arm. His high 34 arm slot team up nicely with that 6’6” frame to create some nice angles, making life very tough on the hitters.

That said, there are some downsides to the delivery, among them is the effort. Each pitch is max effort, it’s not a smooth motion, and there’s some headwhack. Hess has reportedly added some muscle in the weight room during the offseason and hit the heavy chicken and rice diet hard to get there. Better strength and flexibility in his legs and hips could help mitigate some of the minor issues in his delivery and help him repeat consistently. At the end of the day if a delivery works, it works, but there are some negatives baked into the positives here.


While there are two plus pitches to carry a reliever profile, Hess also has shown a changeup that is nothing to write home about. It doesn’t have a ton of movement, and it doesn’t separate itself, velocity wise, from the fastball. He controls it well enough to flash it, but he can run into trouble if he catches too much of the plate because it doesn’t have as much deception as you’d like. Still, two pitches out of the bullpen can work just fine, particularly when both pitches are plus. What needs to improve is his command.

Hess walked 16 batters in 37 total innings across three different leagues in 2019. That was his draft year and there are growing pains, but that needs to improve if he is going to turn into a high leverage reliever. Put simply, the command needs to improve for his pitches to both play to their plus grades consistently. His fastball will sail on him more often that it should, and he has a tendency to spike his slider in the dirt. Dialing in his delivery and spotting quality strikes will be the biggest factor in carrying Hess to his ceiling in pro ball.

Hess is still very young in his baseball career, and he’ll be just 24 for the entirety of the 2021 season. Playing last year would’ve told us a lot more about his numbers because 37 innings is a small sample size. After gaining experience at the alternate site, it will be interesting to see how Hess looks in 2021. If things come together with his command he could move very quickly this season.

Projected 2021 Team: Double-A Erie SeaWolves

Going from West Michigan to Erie based on last years alignment means Hess would skip the Advanced-A level. With the lost season and the positive signals the Tigers have sent about him, the SeaWolves bullpen seems like just the right spot for Hess to continue his development. This may be aggressive, but if he doesn’t start in Erie it shouldn’t be long until he gets there.