Ed Mujica, Polarized Profiles, and Analyzing Baseball Players

By Editorial Staff

What do you think of Padres reliever Ed Mujica?

I’ve seen a lot of answers to that question in various Padres blogs and such, and there seem to be two schools of thought: he’s either a) a very valuable reliever or b) a guy who needs to be DFA’d now!

It’s odd, because such a distribution of opinions doesn’t seem like it would usually exist.

Logically, when there’s several years of pretty consistent data, opinions should come to a general consensus. Sure, there are “love them or hate them” players, like David Wright, Alex Rodriguez, Manny Ramirez, etc. but even those who insist Wright is the problem with the Mets or A-Rod was the problem on the mid-2000’s Yankees would admit they are easily MLB starting-caliber players.

So, small differences of opinion? Sure, they’ll happen. Maybe Observer A thinks a player is ready to break out while Observer B thinks he’s done growing.

It’s usually with prospects or young players with little MLB playing time that the polarized opinions tend to arise, when everyone isn’t debating how good a player is, but how good he will be. Then everyone gets into debates about which skillsets project and which don’t, and that whole can of worms.

But Ed Mujica’s pitched in 147 MLB games now, and the opinion of him is seemingly still all over the place.


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Well, it’s because he has a polarized statistical profile.

It’s one thing to be a ho-hum, average player, like a pitcher with a 4.00 ERA, or a batter who hits .265 with 18 homers and 10 steals.

When we look at guys like that, we glance down the statline, find nothing particularly interesting or distasteful, and go “Average player.” That’s a normal statistical profile.

But then you have a player like, say, Jack Cust of the A’s, who hits .230 or so with nearly 200 K’s per year, but walks about 100 times and bashes 25 homers every season.

With Cust, there’s no balance in his statline. You look at it and go “well, he’s good at this and this, but bad at this and this and this…” and your brain doesn’t really know what to do with that information.

So what happens? Half of Oakland’s fanbase thinks Cust is the best hitter on the team, and the other half wants him cut.

The truth is somewhere in between, as it always seems to be. Cust’s backers are so caught up in his walks and homers that they ignore the significant issues carrying him on a roster presents defensively, and overlook the fact that his slugging percentage is dragged down by a somewhat declining bat and a never-good batting average. Heck, the guy didn’t even slug .450 in a single month last year.

Enough about Cust, though–this article isn’t about him. Point is, when a player has extremely good numbers in certain areas and extremely bad numbers in others, commotion ensues.

Mujica has every bit as polarized a profile. He’s got a career 157/35 K/BB ratio, including an amazing 35/4 this year. But he also is an extreme, extreme flyball pitcher, with just a 35.3% groundball rate and 1.40 homers per nine innings over his career. The homers have ballooned to 2.06/9 this year.

On one side of Mujica analysis, we’ve got those who cite the incredible K/BB ratio. On the other, people criticize Mujica for allowing way too many homers in key late-game situations.

But hey now, let’s slow down. The truth lies somewhere in the middle.

Sure, a polarized profile creates a cognitive dissonance effect for everyone, whether they’re a casual fan or a seasoned statistical analyst. You can’t really add the numbers up in your head with any certainty.

But heck, that’s what composite stats are for! If Mujica allows way too many homers, his ERA, FIP, xFIP, tERA, etc. will likely be bad. If his K/BB totally outweighs the homers, those metrics will be very good.

For batters, we have wOBA and OPS+, and, of course, there’s WAR for everybody.

The bottom line on Jack Cust is that he was a very good hitter in 2007-08 who slipped to league average in 2009-10, which isn’t acceptable for someone with his defensive limitations. The bottom line on Ed Mujica is that he has an ERA of 3.09 this season, which is very much in line with his 3.11 xFIP. Those two numbers were worse but still good (3.94 and 3.93) in 2009. He’s been an above-average pitcher the last two years, but is clearly a notch below the Gregerson/Adams/Bell triumvirate in the back of the Padres bullpen.

So, don’t get confused by polarized profiles like Mujica. They’re a big reason why we use composite stats, even ones as basic as ERA: they do the overall math for us. Don’t try to do it in your head; you’re probably overlooking something.