DL Hall Must Rediscover His Fastball To Become An Effective Starting Pitcher

DL Hall’s first three turns through the Brewers’ rotation have been rocky. In 12 ⅔ innings, the left-hander has produced a 7.11 ERA, 7.44 FIP, and a subpar 15.6% strikeout rate.

Each of those starts has taken a different shape. Hall was inefficient and demonstrated poor command in his season debut. His pitch execution improved in his second start, but the Seattle Mariners still tagged him for three earned runs in a tough-luck third inning. The Baltimore Orioles hit him hard in his latest outing on Saturday, slugging three home runs in 3 ⅓ innings.

What has remained constant through all three appearances is a lackluster fastball, a surprising development given Hall’s reputation when the Brewers acquired him as part of the package for Corbin Burnes in February.

Hall’s heater drew a 70 scouting grade from FanGraphs, and was regarded as the cornerstone of his arsenal. It induced whiffs on 30.2% of swings, while holding opponents to a .266 wOBA last season out of the Baltimore bullpen.

That effectiveness has evaporated in Hall’s first run as a big-league starter. The whiff rate against Hall’s fastball has tumbled to 10.2%, and opponents have torched it for a .494 wOBA. The Orioles tallied five hits against it on Saturday, including a pair of home runs.

Hall’s fastball does not have a single standout quality, but several above-average ones combined to make it a plus pitch. Those traits have regressed to start his Brewers tenure.

He was always going to lose a tick of velocity as he stretched out into a starter, but Hall is suffering from a greater slowdown than expected. His fastball has fallen from 95.6 mph last year to 92.6 this season.

Just as importantly, the pitch has lost a couple of inches of carry, declining from 15.2 inches of induced vertical break to 13.5. That can be the difference between a swing underneath the ball, which produces a whiff, or a harmless fly ball and a barrel.

Lastly, Hall is not throwing his fastball to ideal locations to the extent he used to. After elevating 50.8% of his fastballs with the Orioles last season, he has elevated 41.6% of the ones he has thrown this year. These changes have combined to turn Hall’s fastball from a plus offering into a batting practice pitch.

Hall’s release point and extension have not discernibly changed. He may be battling some other mechanical flaw that is preventing the ball from leaving his hand with conviction. It's not just the transition from relief to starting, or a problem of having left his velocity in Baltimore, because he was up to 97 MPH even this spring, in Cactus League action captured by Statcast cameras. If there's a mechanical problem, it arose some time in late March. A mental block having to do with the goal of working deep into games would better explain the data we have. The big, lurking concern, of course, is an injury, but without any hard evidence of that or a hint of it from Hall or the Brewers, we can only notice a 2.3-MPH difference from his maximum velocity in a multi-inning spring start and his peak on the young regular season and wonder.

Whatever the issue, sorting through it is the first hurdle Hall and the Brewers must clear as they work to develop him into a big-league starter. While his breaking stuff and changeup have shown promise, Hall needs an effective version of his fastball to succeed in any role, and he doesn't have one so far.