Zach Wilt: Breaking down Dylan Bundy's longball issues

No pitcher in baseball has surrendered more home runs this season than Dylan Bundy. In 146 innings, Bundy has allowed 35 longballs, seven more than the next closest starting pitcher. That's 2.16 homers per nine innings, making Bundy the only starter in baseball with more than two.

It's probably hard to remember way back to April, but I'll try my best to refresh your memory. At the end of baseball's first month, Bundy was sporting a 2.97 ERA and seemed to be on track to being the Orioles' best starting pitcher. His ERA and FIP were more than one run lower than the next closest qualified Orioles starter, he was striking out nearly 11 per nine and keeping opponents in the ballpark with a 0.74 HR/9, lowest in the rotation.

Diving into the StatCast data, the decline this season is a bit more disturbing for Bundy. His 9.4 percent barrell percentage ranks in the bottom 4 percent of the league. His 89.1 mph exit velocity is among the bottom 7 percent of the league and .362 weighted on-base average against is in the bottom 2 percent of baseball. All are career highs for the 25-year-old.

The problem is clear, but what is the cause? How has Bundy's HR/9 gone from 1.48 two seasons ago to better than two today? The first place that people look when discussing hard contact is velocity and it's no secret that Bundy's has dropped over his years in the big leagues. When the Birds initially called him up in 2012, Bundy threw gas with his fastball averaging at 95.29 mph according to PitchF/X data from BrooksBaseball.net. After undergoing Tommy John surgery and returning to the big leagues in 2016, his average fastball was down to 94.97 mph. Last season it dipped to 92.48 mphand it's even lower in 2018 at 92.11 mph.

It's no surprise that we've also seen opposing hitters have more success off Bundy's fastball over the years as well. The batting average against has climbed from .167 in 2012 to .277 in 2016, .288 in 2017, and now it's at .296 this season. This is understandable, given the decline in velocity. What's more glaring has been the increase in opponent batting average on Bundy's off-speed pitches. Last season, opponents hit .229 on his off-speed stuff, this year they're hitting .365. That has got to come down. If Bundy can no longer overpower hitters with his fastball, he has to be able to fool them with off-speed pitches.

I tried to find a reason why there's such a difference in the outcome of Bundy's pitches this season. One of the things I noticed was that his release point this season is much higher overall for his fastball, breaking pitches and off-speed pitches. His fastball in particular has a much higher release point at 6.22 feet this season than it did last year at 6.07 feet. Off-speed and breaking pitches have been released at 6.1 and 6.11 feet this season compared to 5.93 and 5.97 feet in 2017. Bundy appears to be getting less horizontal and vertical movement on the fastball with this change in release point, though the difference is minimal.

Bundy's approach has also been overly aggressive this season. He's living in the middle of the plate and hitters are making him pay. On pitches in the middle of the zone, opponents have an .878 slugging percentage. He's been dominant on low and away pitches to righties and high and outside to lefties, but those pitches seem to be all too rare.

I still think Bundy has the tools to be a solid starter for the Orioles, he just needs to refine them a bit. Gone are the days of the upper-90s fastball and the approach has to be to induce more ground balls. The good news is, Bundy's underused sinker has improved since last year. The bad news is, it still has a ways to go. Hopefully, the Orioles can use the data on Bundy to refine his approach and sharpen the skills for 2019 and beyond.

Zach Wilt blogs about the Orioles at Baltimore Sports Report. Follow him on Twitter: @zach_wilt. His views appear here as part of MASNsports.com's season-long initiative of welcoming guest bloggers to our pages. All opinions expressed are those of the guest bloggers, who are not employed by MASNsports.com but are just as passionate about their baseball as our roster of writers.