Player Background

Hahn was an over-slot sixth-round pick by the Rays in 2010 out of Virginia Tech, where he’d made steady progress in refining his command of a fastball that touched the mid-90s. He was viewed as a potential first-rounder by the spring of his draft year, but late-season elbow problems knocked him down. The elbow woes ultimately led to Tommy John surgery shortly after the draft, and he missed all of 2011 rehabbing the injury. The Rays worked him back slowly in 2012 and 2013, limiting him to a combined 121 innings between the two seasons. He dominated the low minors when he took the ball, whiffing a batter an inning and compiling a 2.38 ERA through High-A, allowing just 97 hits. He was shipped to San Diego after the 2013 season in a seven player deal, and he continued to dominate in the Texas League before making his Major League debut in June. After a bumpy first start he reeled off a sick eight-start stretch through the end of July that saw him go 7-1 with a 1.19 ERA, 0.76 WHIP, and just 28 hits allowed across 60 1/3 innings. He tired down the stretch, ultimately finishing the season in the ‘pen, before heading to Oakland as the centerpiece of the A’s haul for catcher Derek Norris.

What Went Right in 2014

Most importantly, Hahn continued to maintain a clean bill of health, more than doubling his previous career high for innings in a season. He showcased a strong across-the-board skill set, checking most of the boxes you want to see checked by a mid-rotation starter. He missed bats at a relatively robust 10.1 percent clip. He burned worms at a top-40 rate among the 161 starters who threw at least 70 innings last season. His in-zone contact rate was among the 20 lowest in the league. And that glorious stretch announced his presence to major-league hitters with authority. It’s slightly cheating to mention this here, but it’s notable that Oakland represents one of the best-case scenarios for a trade destination. Usually when pitchers get traded out of Petco (to the American League, no less), their values stand to take a significant hit. But between a relatively neutral ballpark swap and the chance to now in pitch in front of what projects to be among the best defenses in baseball, the trade turned out to be a rather clear win for Hahn’s value.

What Went Wrong in 2014

Not a whole lot, honestly. The jump in innings appeared to take a toll on Hahn by the time August rolled around, as after the earlier season stretch of brilliance he staggered his way to the finish line while the team limited him to a single relief appearance in early September. It’s tough to tell if his fade down the stretch was entirely the product of fatigue or big-league hitters finally starting to figure him out, however. His release point did drop a bit over his last couple starts, but perhaps a larger issue at play may be tied to what is a relatively limited arsenal. Hahn throws his two fastball variants and a curve about 90% of the time, and once a young starter makes his way through the league once that’s the kind of arsenal hitters can start to figure out. The finish left a cloud of uncertainty hanging over Hahn’s head into 2015 about just what kind of potential he’ll really have as a fantasy asset over a full season.

What to Expect in 2015

That’s the $64,000 question. First and foremost, we should expect an innings cap somewhere in the range of 150 or 160 frames and no more. As Tom Verducci pointed out, Hahn’s 58 percent innings jump last year was far and away the biggest of any starting pitcher, so some caution seems warranted. Whether that involves a mid-season stint in the bullpen or another early shutdown remains to be seen. As far as the stuff goes, Hahn gets dinged for the limitations of his arsenal, but realistically it plays as more of a true three-pitch mix than it appears at first glance. He deployed his two-seam, his four-seam, and his curve with about the same frequency, with each pitch accounting for between 29-31 percent of his arsenal. The thing about his heaters, though, is that they both work at almost identical velocities (92 for the four-seamer, 91.6 on the two) but move in opposite directions. He gets good plane from the extension of his 6-foot-5 frame, and from his high-three-quarters release slot, he generates about seven inches more vertical movement on the two-seamer and another four of east-west. The distinct movement patterns allow each of his fastballs to play up, and in addition to producing solid whiff rates with both variants he generates a whole bunch of off-center—and specifically ground-ball—contact.

The curve is a legitimate swing-and-miss complement, and the change may just be the most important piece of the puzzle. His best month perhaps not coincidentally coincided with his most generous cambio rate against lefties, and while the mere seven mile-an-hour differential isn’t ideal the whiff rate and groundball percentage he flashed with the pitch over his first couple months were perfectly playable. If he’s able to gain some confidence and consistency with that pitch to further solidify his attack against left-handed hitters, look out. And even if he isn’t able to improve on last summer’s results, he’s still got the baseline toolkit to be a solid SP5 in medium-depth leagues (think top-75) for as long as he pitches this season. Owners in roto leagues will need to plan accordingly around the innings limitations, and in head-to-head keeper leagues, he’ll make for a strong upside play for contending teams in the first half with an eye toward shipping him as a featured asset at the deadline.

The Great Beyond

Even if he sticks in the majors from here on out—no given, as he has remaining options and Oakland has a good bit of rotation depth—Hahn won’t be arbitration-eligible until after the 2017 season. So despite Billy Beane’s wheel-and-dealin’ ways, it’s a pretty safe bet he’ll be firmly ensconced in a tasty ballpark environment for the next several years at a minimum. As far as his own performance goes, it’s not exactly rocket scientific analysis, but we should learn a whole bunch about Hahn’s long-term value this season. Some scouts have remained skeptical that his profile can play long-term in a major-league rotation, and while I’m on the bullish end of the spectrum, there are certainly questions to be answered by a (relatively) full season against big-league lineups.

For dynasty-league managers with an eye to the future, he’ll be a guy to watch closely through the first couple of months of the season to see how hitters react to him now that an introductory book has been written and passed around this off-season. The effectiveness of his curve, which got battered down the stretch, and the development of his change will be the key focal points. There’s enough here, though, that restrained optimism is warranted for Hahn developing into a solid mid-rotation asset through his peak years. He’s got the kind of non-velocity-dependent skillset to carve out a long career in that kind of capacity. The upside for more is quite limited, and the downside for less significant. But he’ll enter 2015 as one of the young pitchers best positioned to take a step forward into annual keeper debates for the next half-dozen seasons.

Thank you for reading

This is a free article. If you enjoyed it, consider subscribing to Baseball Prospectus. Subscriptions support ongoing public baseball research and analysis in an increasingly proprietary environment.

Subscribe now
You need to be logged in to comment. Login or Subscribe
For the trivia buffs. Matt Harvey and Jesse Hahn were high school teammates at Fitch HS in Groton, Ct. Harvey's father Ed was the long-time coach there.
Wilson - Enjoyed the write up. Roto question, can you rank Hahn, Stroman, Paxton and Salazar. Thanks.
Thanks! 2015 only? Stroman, gap, Salazar, Paxton, smaller gap, Hahn. I like Hahn more as a 2015 trial balloon with potential to morph into a nice, undervalued longer term asset if he takes another step forward (and I think he will). Other three are basically gloves off, ready to go for this season. Stroman's awesome, he's head and shoulders tops on that list.
Jesse Hahn bowls a "Doosra", good to know :)