So hey, fun fact, have you noticed that Porcello is good? Yeah, of course you have because you have eyes and you’ve probably read this site enough to be aware of his many virtues. I don’t need to recount the numbers, but he’s pitching deeper into games than ever, running a crazy low ERA, matching his career best FIP (essentially), getting lefties out, and pitching better with men on base. He’s tracking toward a 4 fWAR season about maybe even a 5 RA9-WAR year. That would be excellent.

I joked on Twitter this afternoon that I had run out of things to say about him because I’m pretty quick to jump on everything related to the 25 year old hurler. Contract future? Check. Stats? Check. Pitch development? Check. Age and context? Check.

Well shoot, what to say?

One thing that Porcello is doing this year that he hasn’t done since 2009 is post a below average BABIP. This is why his ERA is a good bit lower than his FIP. And presumably, he hasn’t become a BABIP-beater meaning his ERA is due for a touch of regression. That’s okay. A .295 BABIP instead of .276 would still deliver great results. We’ve always assumed his BABIP was inflated by pitching in front of a horrible defense, and it was, so let’s investigate his 2014 and see what we find.

You know the overall pattern, but look how much higher his BABIP vs LHH has been over his career. He only has one rough BABIP year against righties but he has a bunch versus lefties. He averages a BABIP about 37 points higher vs LHH per season and overall and that includes this year. It was in the 40+ point range before that.

Okay, so Porcello’s big BABIP jump is against lefties. Let’s did deeper.

Here are BABIP versus LHH based on batted ball type (via Savant’s classifications):

For analytical purposes, let’s compare 2014 to 2013 and 2011. I think 2012 is just a weird outlier for many reasons. I’m not saying it didn’t happen, it’s just not useful for comparisons. He’s in between on fly balls and line drives but way down on ground balls. Let’s not go crazy due to the sample size, but I think ground balls against lefties are clearly a key factor here.

Let’s dig in.

Let’s look at ground balls versus lefties to the right of 2B and to the left.

Okay, so ground balls to the right of second base from lefties. This makes perfect sense for lots of reasons. Lefties killed Porcello, lefties hit the ball to the right side, and the Tigers had some rough defense over there. Remember 2B before Infante? Remember Prince at 1B? Ouch. So if a pitcher got better against lefties and had better right side defense, you’d expect a BABIP drop. That’s what we have.

But of course, it’s not that simple. Of course there are sample size issues to consider. This is an explanation, not a prediction. If Porcello is truly improving versus lefties and has better right side defense this will continue, but all we can say for now is that this is a big driver in his BABIP improvement and it’s not out of line with other observations.

Let’s do sanity check. Let’s peak at Scherzer’s BABIP versus lefties to the right side too:

Man it’s good to have Kinsler and Cabrera over there.

This seems to indicate that Porcello’s not hugely responsible for the improved BABIP, but this is just the opposite of saying it wasn’t his fault when they let him down in the infield. The Tigers improved their right side defense and it’s allowed Porcello to give up fewer hits to lefties. And that effect can compound because it shortens innings and limits damage.

Porcello’s probably not a ton better than last year, but he doesn’t have to be. He’s finally pitching to a defense that’s capable of supporting him. And as a result, he’s not allowing very many runs. That doesn’t make him a better pitcher but it’s allowing everyone to see the great pitcher he already was.