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Could a move to the bullpen be the key to success for Tyler Chatwood?

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A look at the stats and history of bullpen moves that worked.

MLB: Arizona Diamondbacks at Chicago Cubs
Tyler Chatwood in his last start against Arizona
Patrick Gorski-USA TODAY Sports

The Cubs added Cole Hamels last week and he will make his debut on Wednesday against the Pirates. That created a rotation crunch and the man moving to the bullpen is Tyler Chatwood. It also sets up an interesting opportunity for the Cubs right-hander who has struggled with his command all season. So I took a look at some previous starters who moved to the pen, how they fared, and then some of Chatwood’s numbers to see what the Cubs could expect.

Starters who moved to the bullpen

Andrew Miller came up with the Tigers, Marlins and Red Sox as a starter. From 2007 until his last start in 2011 he started 76 games and while there were moments of brilliance, the underlying numbers were troubling. He struggled with his command, and during that time period his ERA ranged from 5.54 to a whopping 8.54. His K/9 maxed out at 7.88 and his BB/9 ranged from 4.70 to 7.16. In fact, in 2010 he threw 32⅔ innings for the Marlins and his BB/9 rate came dangerously close to eclipsing his K/9 (7.16 and 7.71, respectively).

His move to the bullpen allowed him to harness the power of his slider, and his durability from starting made him a potent multi-inning relief threat. In 2012 his K/9 almost doubled from 6.92 in 2011 to 11.38 in 2012. And while it took him more time to bring his BB/9 rate down to the elite level he demonstrated in 2016 with the Indians and Yankees, there was improvement almost immediately.

Dellin Betances came up through the Yankees minor league system as a starter. He had also demonstrated plus pitches, durability, and some lingering control issues. He didn’t get nearly as long of a tryout as a starter for the Bronx Bombers, however. He managed to last just two innings in his sole start against the Rays. Although, really their concerns about his control might have started during his relief debut the week before. 2011 Betances pitched 2⅔ innings in total. He walked six and struck out two across two games, and the Yankees settled on developing him as a devastating bullpen weapon.

A less dramatic example from the control side, but still an impressive one, is former Cub Wade Davis. As a starter with the Rays Davis was unimpressive. He started 64 games across three seasons for the Tampa Bay Rays. His ERA hovered between 3.72 and 4.45. In 2012 he was moved to the bullpen where he pitched 70⅓ Innings across 58 games. His K/9 more than doubled with the move, to 11.13 from 5.14 and while his BB/9 remained basically unchanged, his ERA dropped two full points to 2.43 with a corresponding 2.78 FIP to match.

This is by no means an exhaustive list, other starters like John Smoltz, Kerry Wood and Tom Gordon all made similar moves to varying degrees of success, and the shutdown middle relief option is currently trending across baseball.

As you can see clicking through the links, pitchers moved for different reasons. Sometimes it was control, sometimes it was age, sometimes it was durability, or a roster crunch. However, all of the success stories managed that transition by utilizing their new role to amplify their strengths and attack their weaknesses.

Can Chatwood do that?

I don’t think Tyler Chatwood is the next Andrew Miller, Dellin Betances or Wade Davis. It would be awesome if he was, but frankly, the Cubs don’t need him to become the best relief pitcher in baseball for this to work. They need him to be a reliable middle innings option similar to Jesse Chavez. There are a few numbers that indicate he could do just that.

First, let’s look at batting average against. Chatwood is harder to get a hit off of than the average major league pitcher, as you can see below:

Chatwood batting average against and MLB average

Second, I broke that out by pitch type. As you can see, all of his pitches are clustered together, but a few are more effective at avoiding hits than others:

Batting average by pitch type
Brooks Baseball

I’ve talked about his ground ball percent before, but it’s worth seeing a visual of how much of an advantage Chatwood has over the league average pitcher here. That’s a pretty handy tool for getting a key double play:

Chatwood GB% and average GB%

Chatwood’s GB percent has contributed to an above average LOB percent, despite his BB/9 of 8.19, which would lead all of baseball if he were qualified. You can see that comparison below:

Chatwood LOB% and MLB Average

One of the things that I found really interesting looking at this data is the amount of tinkering with Chatwood’s repertoire and makeup that has occurred this season. Only needing to pitch one time through the order should simplify that a bit and just allow him to throw his best stuff. Theoretically, that could help him work on his control issues:

Chatwood pitch usage by year
Brooks Baseball

Finally, it’s worth noting that Chatwood has been better his first time through the order this year than later in the ballgame. In 36⅓ innings, the first time through the order he has an ERA of 2.72, in 37⅔ innings the second time through the order that ERA shoots up to 6.69.

The obvious elephant in the room about this move is the aforementioned BB/9. I wish I’d found an awesome answer in the data on that. I would love to be able to tell you, with some degree of certainty that Chatwood will walk fewer guys out of the pen. But I didn’t find that data and I can’t tell you that. The walks are happening early, late, and often. In fact the only indicator I saw that really correlated with his propensity to walk someone was him falling behind in a count 2-0 or 3-0 (which, duh, of course he walks more guys when he falls behind in the count).

However, watching his last few starts I’ve wondered if part of the command problem is in Chatwood’s head at the moment. If it is, a change of scenery could be exactly what he needs in order to get that issue under control. It’s as good of an idea as any the Cubs have tried yet, and he wouldn’t be the first guy to improve his control and effectiveness with a move to the bullpen.