We're too hit-obsessed in fantasy baseball when it comes to evaluating pitchers. Even the breakthrough stats like BABIP still lump all hits together. But of course, all hits are not equal. Extra-base hits are extra bad when it comes to run prevention.
Let's illustrate by solving the mystery of Johnny Cueto. Last year, his low ERA (2.31) was easy for people to explain – he was lucky when it came to BABIP (just .254). As expected, his BABIP corrected this year to .302 (actually worse than league average). But his ERA has barely budged – it's just 2.45. So why the heck is Cueto so stubbornly good? Yes, his strikeout rate is up, but not dramatically (7.1 from 6.0 in 2011). That explains very little. But his slugging average allowed explains a lot. Simply put, most of the hits Cueto allows are harmless singles. The best way to isolate this stat is to look at isolated slugging allowed (slugging average minus batting average) – and Cueto's is a MLB best 0.093.
Skeptics I'm guessing are unimpressed: "Cueto has replaced one fluky number (BABIP) with another (ISO)." But that doesn't pass the logic test. Hard hit balls are exactly the type of thing that good pitchers are supposed to prevent. It's a lot harder to curse the gods of randomness over a ringing double than a seeing-eye single.
But if ISO is more skill than luck, Cueto should have been good at preventing it in 2011, too. Sure enough, his isolated slugging in 2011: 0.84, second best in the majors (Roy Halladay was 0.75). Did you hear anyone say that Cueto was among the leaders in ISO allowed last year? I did not. And now he's repeated this excellence. Last year, the low batting average was actually distracting us from what's more important – the softness of the hits he actually does allow.
So we don't make this mistake again in 2013, let's document the current leaders among starters who qualify for the ERA title in best ISO (stats through Tuesday):
Right away, you know you want Parker and Masterson next year. In fact, I'm going to try to get Masterson in my 20-team dynasty league as soon as offseason trading begins (just like I got Cueto last offseason – for Michael Brantley). But the short of it is that basically these guys should have been among the ERA leaders, so those who are not are going to be cheaper than they should be.
I know: Derek Lowe. Well, he's a million years old and probably on his way out of baseball, so we won't have to worry about him being an outlier. But here's a rule to supplement the ISO rule: if the K/BB is 1.00 or less (as it is with Lowe), you pass.
Note also that the guys on the list this year ranked great-to-better-than-average in the stat last year. Vogelsong, for example: 17th best in 2011.
Now the other end of the spectrum, the worst ISOs:
Who cares, all these guys stink, right? Not in the eyes of many, though, who are eager to make excuses for them. Max Scherzer is the best example. I picked up Joe Blanton for his K/BB ratio in the Yahoo! Friends and Family League a couple of weeks ago, before coming to my senses. I lead the world in making Edwin Jackson excuses (we all have our weaknesses). Hughes still has his fans. So does Floyd and Latos. Even Jimenez is always a couple of good starts away from being added by a lot of smart guys I know. But wise up, people. These guys all give up hits that are simply too loud to support nice, calm and quiet ERAs.
And for the record, Haren and Latos were middle tier in the category last year – 39th and 37th respectively. If you would have just assumed they'd be 39th and 37th this year in ERA (worse for Latos adjusting for park factors), you would have passed at their ADP and been better off. And Hellickson, another guy I fell for hard this year but never will fall for again, was 80th last year in ISO. So that to me is much better evidence that he was lucky in 2011 than his BABIP allowed. Yet it was largely ignored.