Joba’s Slide: Regression, Bad Luck, or Something More?

Clip art illustration of a Cartoon Tiger with a Missing Tooth

It’s been kind of a weird season to be a Tigers fan for a few reasons. It hasn’t been weird that the bullpen has struggled but it was pretty weird that the biggest question mark of the bunch was the steadiest arm for the first few months of the season. Joba Chamberlain was risk, a fine one, but a risk nonetheless. And for a while, it looked like Dombrowski had cooked up another pot of magic. And then, things went south.

Let’s dig into the first and second half splits for Joba. The All-Star Break is arbitrary. But it’s all arbitrary. I could split it from August 1 or July 25. It doesn’t really matter.

Split IP TBF K% BB% HR/9 BABIP
First Half 37.2 151 26.5 8.0 0.24 0.313
Second Half 19.2 89 15.7 11.2 0.92 0.323

Joba’s strikeout rate is down, the walks are up, the home runs are up, and the BABIP isn’t much higher. Those are bad signs. Granted, it’s a very small sample and we can’t make too much of it, but all of the indicators are trending in the wrong direction.

Let’s check the results:

Split wOBA ERA FIP xFIP
First Half 0.268 2.63 2.46 2.84
Second Half 0.348 5.03 4.70 4.33

Nothing surprising here, either, but plenty to make you concerned. This isn’t simply a little batted ball luck or a poorly timed home run. Joba’s peripherals are bad and so are his results. What’s going on here?

There are essentially three possible options. Bad luck, regression, or some sort of change in his process and talent. The bad luck doesn’t hold water because his K/BB/HR numbers are all moving negatively and his BABIP isn’t. That’s not what bad luck looks like.

So we’re really asking ourselves if Joba got demonstrably worse or if this is simple a matter of regression and random variation? Was he just over-performing during the first half, leaving this as a market correction? Or did he forget how to pitch?

Let’s start with a peak at his preseason projections (Steamer). Granted, projections for relievers (especially ones with injury histories) are to be taken with a grain of salt. But let’s look anyway:

K% BB% HR/9 BABIP ERA FIP
Projection 20.6 8.4 0.96 0.291 3.92 3.90
2014 22.5 9.2 0.47 0.316 3.45 3.22

This is pretty interesting. Steamer (which thought more of him than over projections), actually expected him to be worse than he’s been to date. He’s getting more strikeouts, limiting home runs better, and running lower ERA and FIP even after the post break swoon. You could look at this table and assume that Joba’s struggles are just things evening out. You might be right, but let’s look a little bit more closely to be sure.

I didn’t find much in his pitch usage or velocity, but let’s look a little bit at location.

He seems to be having more trouble filling up the strike zone since the break, and that’s not a surprise given the walk rate.

Split Z Swing% O Swing% Contact% Zone% F-Strike%
First Half 56 28.8 72.6 50.7 60.9
Second Half 61.9 27 78.2 47.3 56.2

Batters are going after his strikes more often and they’re connecting. He’s also throwing fewer strikes and fewer early strikes in the second half. It’s hard to say if this lack of command is just a bit of noise or if it’s deteriorating over time, but it’s certainly not helping his case.

My bet is that Joba pitched above his talent level during the first half and is pitching a little below his talent level right now. I’m not worked up about the fact that he’s getting worse because I think it’s probably safe to say he’s a high 3’s ERA and FIP guy. Relievers like that are going to go through good times and bad. We have enough information to know he’s not that lights out relief ace he was in the early goings, but I also think we have enough information to suggest that he’s not totally useless.

This isn’t an encouraging finding, but it’s probably also not doomsday. Joba is an okay reliever. That’s who the Tigers signed. They just happened to get a couple of great months out of him before he came back to Earth.

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