Does Dylan Bundy Struggle Against Left Handed Batters?

Last week, Dave Cameron wrote a post over at Fangraphs talking about how terrible the Orioles starting rotation is. This is not news, and Cameron isn’t the first to write about that particular subject this season. The piece itself mainly focused on Kevin Gausman and Chris Tillman, but Cameron included a little tidbit in his article discussing Dylan Bundy and how he needs to figure out a way to get left-handed batters out. Specifically, here is what Cameron said about Bundy.

"The AL average K%-BB% for a starting pitcher is 12.2%, a mark that no member of the Orioles rotation is living up to. Bundy is close to that average, and combined with batted-ball tendencies that make him look like he might be a guy who can legitimately avoid hard contact, he’s a perfectly decent big league starter, though he won’t be any kind of ace until he can figure out how to get lefties out more effectively."

This took me by surprise, as I did not think Bundy was doing all that badly against left-handed batters. So based on Cameron’s statement(s), I thought I would take the time to investigate a little bit further.

Dylan Bundy (photo via Keith Allison)

Based on the initial look at his numbers in 2017, Bundy is performing worse against left-handers than he is against right-handers, but not by much. To date, he’s allowed a .245/.315/.420 (.313 wOBA) against left-handed batters compared to a line of .232/.288/.411 (.299 wOBA) against right-handed batters. So while there is a difference, it doesn’t strike me as some massive problem that Bundy needs to figure out. The numbers for his overall career show a similar result. Lefties hit Bundy better than righties do, but again, not by much (.320 wOBA versus .317 wOBA). So what is the basis of Cameron’s statement? I am not entirely sure as I can’t read his mind (and he didn’t expand the Bundy comment further within that piece), but I am guessing that it has to do with strikeouts.

Dylan Bundy is having a great year for the Orioles, and he’s essentially been the lone bright spot in a rotation that has been extremely disappointing to date. Having said that, Bundy has been getting the job done with a less than stellar strikeout rate. He has the best K%-BB% of any Baltimore starter, but even that is less than that of the league average starting pitcher. If you break it down further and look at the batter handedness splits for strikeout rates, that’s when one starts to see potential issues.

Bundy’s strikeout rate versus left-handed batters is only 12.4%, which is a full 10.1% lower than his strikeout rate against right-handed batters. Combine that with an 8.6% walk rate against LHB (2.3% higher than that against RHB), and he’s left with a measly 3.7% K%-BB% against left-handers. While Bundy does not have a lot of time in MLB prior to last year, this issue does appear to be new in 2017. It’s not necessarily a huge problem, but it is a concern if Bundy’s low BABIP, high LOB%, and low HR/FB rate against left-handed batters start going in the other direction (although, he also has a low BABIP and high LOB% against RHB as well).

So let’s break this down further and look at Bundy’s pitch mix in 2017.

Dylan Bundy Pitch Usage in 2017 (via Brooks Baseball)

Just looking at the overall pitch usage, the only general difference in Bundy’s approach (all counts), is that he’ll swap out sliders for changeups when he faces left-handed batters. That’s pretty typical, as a good changeup can be a pretty effective pitch for neutralizing batters who hit from the opposite side. However, Bundy’s changeup (even with a pitch value of 10.1 runs above average, according to Fangraphs), has not been good at putting left-handers away. Bundy gets a whiff/swing rate on his changeup against left-handers of 24.10%, which is actually lower than the 27.27% whiff/swing rate he gets with his slider against left-handers. Compare that to the whiff/swing rate of 51.28% using his slider against right-handers and it begins to look like the changeup may not be a good out pitch for him against left-handers. To Bundy’s credit, he’s locating the changeup really well against left-handers, which could help support his decent line against them for the year.

Dylan Bundy Changeups Versus LHB in 2017 (via Brooks Baseball)

So maybe Cameron was right when he stated that Bundy won’t be any kind of ace until he can get left-handers out. Or maybe he was only partially right. It’s true that Bundy isn’t getting the whiffs or strikeouts against left-handed batters you’d like to see from a top of the line starter. However, his results against left-handers isn’t so much worse than the results against right-handers that the team should start getting worried. While it would be nice to see left-handers swing through the changeup more often, just because left-handed hitters aren’t missing it, doesn’t necessarily mean Bundy isn’t fooling them, as Bundy is holding left-handers to a .136 batting average and a .205 slugging percentage on the changeup. Combine that with the evidence that Bundy appears to be able to command the changeup against left-handers very well, and I think this (at least for now) is a non-issue. We’ll just have to wait and see if it ever becomes one.