When a team selects a player in the Rule 5, it’s a success if said player simply manages to stick on the 25-man roster all year. By that measure, Daniel Stumpf was a clear win for the Detroit Tigers in 2017. Not only did he stick, but Stumpf showed himself a capable lefty specialist who still has the potential for more.
Stumpf struck out 20.4 percent of hitters last season, which is a little below average, but still respectable. Less respectable was a walk rate of 9.4 percent (3.58 per nine innings). Overall he posted a FIP of 4.49, with a 3.82 ERA on the year. Predictably, he kept the ball on the ground to limit left-handed hitters to just a .280 wOBA, but was knocked around pretty badly against righthanders.
So, we have a 27-year-old reliever who has shown himself useful, but has yet to establish himself as a major league regular for the long haul.
Stumpf’s changeup is the key
If Stumpf is going to turn himself into something more than a fringe middle reliever who can stymie left-handed hitters, Stumpf is going to have to find a weapon to neutralize righthanders. The obvious answer lies in his changeup. To that end, he and pitching coach (and former big-league pitcher) Woody Williams spent the offseason working on the pitch.
The challenge Stumpf faces is to throw a slower version of his changeup to create better separation from his fastball. Doing so without losing arm speed and deception on the pitch is the trick. Stumpf feels like he has made pretty good progress this offseason, as Anthony Fenech reported recently for the Free Press.
“I’ve been working on it a lot and the grip change has been more comfortable,” he said. “Even though I haven’t been clocked yet, I feel like it’s getting up there slower than normal.”
The adjustment makes good sense as long as he can command it. Stumpf averaged 93.7 miles per hour with his four-seam fastball last season, yet his changeup averaged 86.9 mph. A separation of six or seven mph is okay, but not ideal for a pitcher often looking to locate his fastball at the top of the zone. One would like to see a bigger gap to generate more whiffs. Typically, the more valuable changeups in the game play at eight to 10 mph slower than the pitcher’s fastball. Stumpf’s stated goal is to throw his changeup closer to 82 mph. So far, his changeup velocity has been in that desired range in his spring training outings.
Assuming he can maintain deception at that velocity, hitters are a little more likely to swing over the pitch or be caught badly out in front of it. If he is able to get the changeup to that point with good arm speed and depth, it should play better off of his high spin fastball. Hitters will have to be prepared to climb the ladder on a pretty crisp fastball while contending Stumpf’s slider. Add a 82-83 mph changeup capable of looking like a fastball out of the hand, but which completely vacates the strike zone by the time it reaches the plate, and that is a better set of pitches to take on right-handed hitters.
Stumpf is a lock to go north
So far this spring, Stumpf has spun 4 2⁄3 innings, allowing one run on two hits. His three strikeouts don’t indicate a breakout there, but spring numbers mean little. It will take months to know if Stumpf has actually found something in his changeup to provide sustainable success. Yet without having to do a lot, Stumpf already looks like the team’s best left-handed reliever by default.
Travis Wood has already gone down for the season with a knee injury. Blaine Hardy has battled shoulder issues and is running out of time to prepare himself for Opening Day. Jairo Labourt was designated for assignment and lost. Right now, the Tigers have Daniel Stumpf and Francisco Liriano as the team’s likely lefties in the bullpen when the season opens. Other than Hardy, or possibly Chad Bell, there isn’t another option anywhere in camp.
At 27 years old, Stumpf is running out of time. He has enough stuff to keep teams interested, but 2018 is the season for him to seize a role. While a better changeup would help him, he still needs to improve his fastball command as well. The odds that everything will finally come together aren’t particularly good. A true breakout season is probably beyond him, but if he’s going to move beyond a career on the fringes of the major leagues, the time is now.