Is Dylan Bundy an Ace on Extra Rest?

Dylan Bundy opened this season with a very good start, throwing seven shutout innings with seven strikeouts and just one walk against the Minnesota Twins. Due to an off-day, Bundy could have pitched on normal rest April 3, but the team opted to pitch Mike Wright, giving Bundy an extra day of rest before his start against the Astros. That’s not unusual–many teams opt to go with five starters early in the season even with extra rest. However, manager Buck Showalter seemed to indicate that this decision was directly due to Bundy’s own unique history.

Dylan is very important to us and just because somebody is feeling good and is throwing good, that doesn’t mean you push them more. We do everything possible to keep everybody on our staff healthy.

Showalter went on:

But with Dylan, we’re going to take every opportunity for that. We want him around for the long haul. Just because he got through last year healthy, doesn’t mean that we throw caution to the wind. We’re not going to do that.

Bundy debuted in 2012, but only pitched in two games. He missed 2013 with Tommy John surgery, and subsequent arm issues prevented him from returning to the majors until 2016, when he split time between the bullpen and rotation. He finally pitched a full season in 2017, making 28 starts and putting up a solid 4.38 FIP, 4.24 ERA and 2.7 WAR in a promising campaign. He was eventually shut down after three September starts–two of them poor–but the season has to be considered a positive one given his injury history.

Bundy has erased some doubts about his shaky end to 2017 with two strong starts this year. In his second, facing the vaunted Astros, Bundy pitched six innings, striking out eight batters while walking just two, and gave up two runs, only one of which was earned. After Wednesday’s game, Bundy had a 1.35 FIP, 0.69 ERA and was MLB’s WAR leader among pitchers. He’s mixing in a sinker more, but for the most part, he’s the same pitcher he was in 2017 when he was good and getting a lot of hitters to chase his excellent slider.

Eduardo Encina of the Baltimore Sun discussed the issue several times last year, including in August, when Bundy remained slightly skeptical of the extra games theory.

“I don’t think anyone is ever going to know if it benefits you or not,” Bundy said. “Sometimes it doesn’t benefit you and you’re out there a little wild, a little rusty. But tonight I think it definitely worked in my favor and I felt great out there.”

While extra rest this early in the season might be seen as taking the long view, there’s some evidence to support the idea that giving Bundy extra rest helps him right now. We don’t have a big sample to deal with, and there are quite a few variables to contend with– such as opponents, park, and time of the year –but let’s take a look at 2017 and see if it provides some support for the contention that Bundy performs better on extra rest. The table below shows the relevant statistics comparing extra rest with normal rest.

Dylan Bundy 2017 Performance
Normal Rest 77 18.3% 9.5% 4.68 5.16
Extra Rest 92.2 24.8% 5.4% 3.88 3.74

Last season, Bundy got much better results pitching with extra rest. His strikeouts were way up, while walks, ERA, and FIP were all down. If we break things down into even smaller samples, the difference is even more extreme. Witness the breakdown of the extra rest.

Dylan Bundy 2017 Performance by Days of Rest
4 Days Rest 77 18.3% 9.5% 4.68 5.16
5 Days Rest 55.2 22.8% 7.5% 4.69 4.42
6+ Days Rest 37 28.0% 2.1% 2.68 2.73

Here we see that as rest increases, Bundy saw gradually better results. This is interesting data, but doesn’t come to close to anything conclusive. Dylan Bundy was at his best at the very beginning of last season and then in August. Here’s a different breakdown of Bundy’s season by date.

Dylan Bundy 2017 Performance by Date
4/5/17-4/21/17 26.1 20.4% 4.1% 1.37 2.09
4/26/17-7/23/17 93 18.1% 8.8% 5.42 5.87
8/1/2017-9/18/2017 50.1 29.6% 5.9% 3.58 2.84

As opposed to the extra day’s rest narrative, the above stats might say that a fresh Bundy at the beginning of the season was good. Then, he slowed down as the season wore on. Then, after the All-Star break and a few other longer breaks, he finished the season well. We can test this narrative a bit by looking at how hard Bundy was throwing during these periods. First, the above chart with four-seam fastball velocity by time period.

Dylan Bundy 2017 Velocity by Date
Date IP K% BB% ERA FIP FA Velocity
4/5/17-4/21/17 26.1 20.4% 4.1% 1.37 2.09 92.4 MPH
4/26/17-7/23/17 93 18.1% 8.8% 5.42 5.87 92.3 MPH
8/1/2017-9/18/2017 50.1 29.6% 5.9% 3.58 2.84 92.7 MPH

There’s some difference, but not too much. If we just looked at August velocity, when Bundy was at his best–see this Jeff Sullivan piece from the end of August–his fastball that month averaged 93 mph. Velocity, as it does with most pitchers, played a role in Bundy’s success. What if we split up the velocity by days of rest? It looks like this.

Dylan Bundy 2017 Velocity by Days of Rest
Rest IP K% BB% ERA FIP FA Velocity
4 Days Rest 77 18.3% 9.5% 4.68 5.16 92.2 MPH
5 Days Rest 55.2 22.8% 7.5% 4.69 4.42 92.6 MPH
6+ Days Rest 37 28.0% 2.1% 2.68 2.73 92.6 MPH

Bundy threw a little bit harder on extra rest and performed better. That’s still not enough to be conclusive, but it is encouraging enough to be worth a shot. It is important for the Orioles to keep Bundy healthy, and if extra rest might help, then they need to try it. There are more off-days this season than in year’s past so it should be easier to give Bundy the extra rest he needs. Is Bundy an ace? The words of Jeff Sullivan are just as true now as they were last August.

Whether it’s all because Bundy was more rested, I couldn’t tell you. And there should still be some amount of caution here, given Bundy’s increasing workload. The Orioles know they can’t just squeeze Bundy here for every last drop. But this is something to build on. This is the latest potential flash of Dylan Bundy’s developing ace-hood. Perhaps he’s not there just quite yet. But if Bundy gets there one day, he’s going to look like how he’s looked lately. The Orioles’ rotation needed a savior, and Bundy emerged, just like how they always had it drawn up.

The Bundy we’ve seen in the early going looks a lot like the one from last April and August when he was at his best. He’s still just 25 years old and hopefully has many healthy years ahead of him. If the Orioles are going to contend this season, they are probably going to need to see this version of Bundy all six months of the season.


Craig Edwards can be found on twitter @craigjedwards.

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5 years ago

Is it foolish to think that more pitchers probably don’t benefit from this, too? Maybe the 5 man rotation is outdated – maybe it SHOULD be 6 man?

I have to assume there is an article somewhere that the 5 man rotation provides the most optimal rest for pitchers and most probable benefits, but it’s hard for me to imagine that an extra day regularly wouldn’t help more players, maybe even more struggling prospects or high velocity guys?

Anyway, great article, very interesting!

5 years ago
Reply to  Kevbot034

I guess it’s partly tradition, but given the constraints of the 25-man roster, going to 6-man undoubtedly means compressing your bench or bullpen.

NPB teams do use 6-man rotations, but they have more flexible rosters, and it’s easier to shuffle players between the first and second division teams.

5 years ago
Reply to  LHPSU

That’s true, but if you are 6 man rotation, you might possibly be able to get a bit deeper into games, theoretically? No idea if that would play out at all, or if long relievers maybe continue to rise in importance (Miller and Bradley, but possibly Hader now, too) for teams and how that could affect things.

5 years ago
Reply to  Kevbot034

Well there’s the problem of pitchers being less effective 3rd time through the lineup, and there’s only so much work you can do in a day, no matter how much you’ve rested.

Would NPB teams be more effective if they switched to a 5-man rotation and deepened their bullpen? Who knows?

5 years ago
Reply to  LHPSU

That’s true, but the less mileage on the arm throughout the week has to help with that somewhat, wouldn’t it? At least maybe decrease a bit how drastically the 3rd time through the order is.

5 years ago
Reply to  Kevbot034

Why would you *want* a larger rotation? A 6-man rotation means giving starts to your 6th-best starter that otherwise would otherwise be handled by one of your 1st- through 5th-best starters.

The only argument in favor of a larger rotation is that it improves outcomes by keeping pitchers healthier. But the 5-man rotation has not actually proven to be less harmful to pitchers than the 4-man rotation. So it’s quite possible that the 5-man rotation (let alone the 6-man rotation) is simply an accident of history based on flawed thinking.

Dylan Bundy’s improved performance on an extra day of rest can simply be attributed to random variation.

5 years ago
Reply to  ND12

I am suggesting a 6 man rotation *might* make your pitchers better. If an extra day of rest makes Bundy so much better, why might it not for many others? And I think this article proves in Bundy’s particular case, that it is not random variation. That’s a pretty decent sample size.