Is Ross Detwiler better suited for the bullpen?

Is Ross Detwiler better suited for the bullpen?
March 18, 2014, 2:00 pm
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On Monday Nationals manager Matt Williams made the surprise announcement that Ross Detwiler will begin the season in the team's bullpen. Though Detwiler was pitching poorly through three spring starts, he was the favorite heading into the fifth starter competition, and was only given three outings to prove his case.

So, now that Detwiler is starting the year as a reliever, what's next for him? Will he succeed in his new role?

There is a bit of a sample size for Detwiler who has 16 relief appearances to his name. He made five in 2011 and a career-high six in 2012. Those 16 games sort out to a total of 32 1/3 innings pitched out of the bullpen.

Here are how his splits look between starting and relieving:

Starter - 69 G, 17-29, 4.02 ERA, 1.395 WHIP, 375.2 IP, 5.3 SO/9, 1.89 SO/BB, .414 SLG%
Reliever - 16 G, 1-0, 1.11 ERA, 1.052 WHIP, 32.1 IP, 6.4 SO/9, 1.53 SO/BB, .255 SLG%

As you see, it's not really even that close. Detwiler has been a more effective pitcher so far in his career when coming out of the bullpen.

There may be good reason for that, as when Detwiler has started, there has been a steep drop-off in his effectiveness after the first two innings. Look at his numbers broken down by the specific innings he's pitched:

Innings 1-2 - 1.82 ERA, .230 BAA
Innings 3-6 - 4.68 ERA, .297 BAA

Also consider his numbers by pitch count:

Pitch 1-25 - .226 BAA, 2.41 SO/BB
Pitch 26-50 - .266 BAA, 1.73 SO/BB
Pitch 51-75 - .306 BAA, 1.97 SO/BB

Of course, most pitchers get tired as the game wears on, and it's often pitchers will become less successful as their pitch counts get higher. But the difference between Detwiler and other Nationals starters, for comparison, is significant.

Look at how Stephen Strasburg, Jordan Zimmermann and Gio Gonzalez have progressed through games during their careers:


Innings 1-2 - 3.20 ERA, .224 BAA
Innings 3-6 - 2.86 ERA, .215 BAA

Pitch 1-25 - .226 BAA, 3.31 SO/BB
Pitch 26-50 - .219 BAA, 4.36 SO/BB
Pitch 51-75 - .211 BAA, 4.72 SO/BB


Innings 1-2 - 2.91 ERA, .228 BAA
Innings 3-6 - 3.43 ERA, .254 BAA

Pitch 1-25 - .234 BAA, 3.46 SO/BB
Pitch 26-50 - .249 BAA, 4.83 SO/BB
Pitch 51-75 - .253 BAA, 4.31 SO/BB


Innings 1-2 - 3.86 ERA, .245 BAA
Innings 3-6 - 3.50 ERA, .226 BAA

Pitch 1-25 - .240 BAA, 1.88 SO/BB
Pitch 26-50 - .216 BAA, 2.79 SO/BB
Pitch 51-75 - .254 BAA, 1.98 SO/BB

All three maintain good numbers through the first six innings. Strasburg, in particular, gets significantly better as the game wears on.

As Detwiler moves later into games, however, opponents tend to find more success off him. While it's common for batters to fare better the second and third time they see a starting pitcher in an average game, the breakdown for Detwiler by plate appearance shows dramatic results.

Times facing Detwiler in game as starter:

1st PA - .225 BAA, .631 OPS
2nd PA - .300 BAA, .787 OPS
3rd PA - .324 BAA, .873 OPS

Detwiler is much better against batters the first time around, and that also shows in relief situations. Opponents have hit just .178 against the lefty in their first plate appearance against him out of the bullpen.

Detwiler has also always relied heavily on his fastball, and has been using it more and more over the years. Last year he threw it 88 percent of the time, that's up from 80.3 percent in 2012 and 73.5 percent the season before.

The sample for Detwiler's career as a reliever is still relatively small at 32 1/3 innings, but he has enjoyed obvious success out of the bullpen in the past. The Nationals could be banking on that premise and see him as more valuable as a lefty reliever than out of their rotation as a starting pitcher.

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