It’s Time for the Cardinals to Shake Up Their Bullpen

Sunday morning, I was talking with Craig Edwards and some others in the lobby of a New York hotel. Craig, who as you probably know runs the Cardinals’ site Viva El Birdos in addition to his work for FanGraphs, lamented Trevor Rosenthal’s “shaky” performance this season. After checking in on Rosenthal and the Cardinals’ bullpen, it is even more clear than it already was that Craig is a kind man, for I would use other words to describe Rosenthal’s performance. It might be time for manager Mike Matheny to make a change at the top of the Cardinals’ bullpen.

I want to start by examining Rosenthal’s walk rate, which currently stands at 17.9% this season — easily tops in the majors among 163 qualified relievers. But it’s not just a bad walk rate relative to the 2016 season — it’s a historically bad walk rate. Since baseball integrated in 1947, Rosenthal’s 17.9% BB% is the 25th-worst mark. That’s 25th-worst out of 6,637 pitcher seasons. As in, that’s really, really bad. If we were to bucket the ERAs of the 24 pitchers worse than him, it would look as such:

• 6.00+ ERA: 5
• 4.00+ ERA: 16
• 3.99 or lower ERA: 8

Looking at FIP is even worse. There’s Aroldis Chapman in 2011 with a 3.29 FIP, and Scott Williamson in 2000 with a 3.38 FIP, and then the lowest remaining FIP is 3.83, with the range going all the way up to 6.35. The majority of the pitchers on this list finished at sub-replacement level, and all but three of them failed to record as many as 10 saves in their respective seasons.

Because Matheny has stood by his man, Rosenthal is poised to become the fourth pitcher in the bottom 25 with 10 or more saves. And were it just walks, you could make the case for sticking with Rosenthal. After all, he’s coming off of two straight 40-plus-save seasons, his velocity isn’t diminished, and he’s maintaining the same contact rate he did last season. This is the guy who struck out nine Red Sox batters in 4.2 innings in the 2013 World Series, and was credited with one of the Cardinals’ two wins in that Fall Classic. Trevor Rosenthal is nails, right?

Well, no. Not right now he isn’t. Because walks aren’t Rosenthal’s only issue. He’s also allowing drastic career highs in both home-run rate per fly ball (HR/FB) and BABIP — 20% and .412, respectively. Only 13 other current qualified relievers have a worse HR/FB than does Rosenthal, and only one has a worse BABIP. Rosenthal’s hard-hit rate (Hard%) also is easily the worst of his career. He’s recorded a 37.7% Hard% right now, and he’s never before been higher than 27.4%. Sometimes, it’s not really bad luck. Sometimes, you’re just getting smoked.

As I said earlier, Rosenthal is rocking the same Contact% he did last year, and he’s still striking out plenty of hitters — even more than last year, actually. But he’s no longer as adept at making hitters take the bat off their shoulders. Currently, there are 82 qualified relievers who were also qualified relievers last season. Of them, just four have seen a bigger dip in their O-Swing% than has Rosenthal. None have seen a bigger drop in their Z-Swing%. And just one, Jonathan Papelbon, has seen a higher drop in Swing%. Let’s take a look at the top five droppers in all three categories.

Swing% Declines for Qualifed RPs, 2015-2016

Pitcher	O-Swing%	Z-Swing%	Swing%
Jonathan Papelbon	6.90%	7.60%	8.80%
Trevor Rosenthal	8.50%	12.70%	8.60%
A.J. Ramos	9.40%	8.30%	8.40%
Arquimedes Caminero	0.60%	10.40%	8.00%
Jim Johnson	8.30%	7.30%	8.00%
David Robertson	9.10%	2.30%	5.20%
Mark Lowe	9.30%	-3.90%	3.40%
Alexi Ogando	10.60%	1.80%	3.10%
Jeanmar Gomez	-5.80%	8.30%	2.30%

(Just to be clear, the way you should read this is Rosenthal’s Swing% declined by 8.6%. I realize it might look a touch confusing. Forgive me.)

As you can see, Rosenthal is the only pitcher who finds himself in each of the three categories. Hitters aren’t afraid of his stuff anymore, and that’s also borne out in his pitch-type data. The three pitches he throws the most — fastball, slider and changeup — have all been far less effective than normal.

If the Cardinals weren’t sweating every single game in pursuit of a Wild Card berth or if they didn’t have a viable alternative, you might be tempted to let him figure this out all on his own, or maybe just give him a few days off from the close’s role. But the Cardinals are sweating every game, and they do have a viable alternative in the person of Seung Oh. Oh has not yet been trusted in the extreme pressure situations for as long as Rosenthal has been: the average leverage index when he’s entered games this year (gmLI) is just 0.95 — and just 1.05 over the last 30 days. But in the last 14 days, that has ramped up. His gmLI during that stretch is 1.47. Oh has been more than up to the challenge in this time, and really has been all season.

The Cardinals have lost their last five games, and make no mistake, there is plenty of blame to go around. They’ve only scored 10 runs in those five games, and it’s hard to win when you’re averaging two runs per game. But that doesn’t mean the team should ignore what’s going on with their closer. Trevor Rosenthal has been at the head of a middling bullpen, and his failure on all fronts this season should lead Mike Matheny to make a change, at least until Rosenthal can figure out how to make hitters swing at his pitches again.