Mariners Draft Profile: Oregon State LHP Cooper Hjerpe
Oregon State left-handed pitcher Cooper Hjerpe is a very fun pitcher in this year's draft. He has a very well-rounded repertoire, but he stands out for his deceptive delivery.
Like Mariners' elite bullpen arm Paul Sewald, Hjerpe has a very low release point, which makes the ball hard for both left-handed and right-handed batters alike to pick up. He also has a little cross-fire in his delivery that makes it especially difficult to distinguish his breaking ball and changeup from his fastball.
Some draft outlets have compared his delivery to that of Brewers All-Star reliever Josh Hader. The way Hjerpe spins the baseball is counterintuitive to his delivery, which means hitters almost have to change their expectations entirely for how the ball will move relative to his arm slot after it leaves his hand. Hjerpe's release points just aren't something you see from a starting pitcher.
Hjerpe does not have crazy stuff, to be sure. His fastball sits 89-93 MPH and he has multiple variations of his breaking ball that he pairs with his changeup. His low-velocity fastball has just average movement, but that doesn't matter; his flat delivery (more specifically, his vertical approach angle) is elite, which correlates well with strikeout rates.
Normally, pitchers with low release points work the strike zone horizontally, but Hjerpe is able to generate a lot of vertical movement, which is very difficult and rare for someone with his release point. He also gets great extension towards home plate, which can help the perceived velocity of a pitch be significantly higher than its actual velocity.
These characteristics effectively result in Hjerpe's fastball playing above what its average spin rates and velocity would suggest. While his breaking balls average 15 inches of horizontal break, it also plays well off his fastball. The fastball and slider have a difference of 16 inches in induced vertical break, meaning that they look similar out of the hand and they would end up in completely different locations if it looked like a pitcher was throwing each of them in the same spot.
Hjerpe's changeup is also pretty good, as its spin rate is very similar to his fastball, meaning that the two pitches look nearly identical. His repertoire and deception complement each other very well.
Some scouts are hesitant about the reliever-risk associated with Hjerpe. The argument is that: since there are not a lot of starters with similar deliveries, he might be a bullpen arm long-term. This would not be an ideal for any team that selects him in the first round; teams want to select pitchers who have a chance to start long-term because they are more valuable and harder to find. A team would not want to spend significant draft capital on a reliever when they could always find interesting arms in the second round and beyond. Relievers can only provide so much value at the major league level.
Fortunately for Hjerpe, there is a belief he projects as a mid-rotation starter. Many scouts think his delivery is repeatable and clean, and he has a great feel for the strike zone.
In 2022, Hjerpe had a 43 percent strikeout rate and a 44 percent groundball rate—both of which are great. Whiffs and groundballs generally correlate to success; pitchers who give up a disproportionate amount of fly balls and line drives run into more trouble than pitchers who can keep the ball out of play or on the ground.
Hjerpe had 161 strikeouts and just 23 walks in 103.1 innings this year, which is elite. He does not walk batters and he really controls the zone. He also only gave up three home runs.
It's possible Hjerpe could start in a major league bullpen for a team straight out of the draft, similar to White Sox pitcher Garrett Crochet. The Mariners should be targeting Hjerpe if they want a college pitcher at pick No. 21.
