If you’ve watched baseball over the last four seasons, you know that the Tigers have had an excellent collection of starting pitchers. They get lots of strikeouts, don’t issues a ton of walks, and generally do things that lead to run prevention. Although, if you’re a slave to ERA, you’ve probably underrated them a bit. Everyone knows why. For years, the infield defense has been pretty rough. 2011 was a year of flux, with a mishmash of 2B and 3B, and 2012-2013 they used a corner infield tandem that could only be described as “good hitters.”

That’s okay, the Tigers prioritized strikeouts on the mound to soften the blow and prioritized hitting the ball very hard to justify the weak defenders. It seemed to be a self-aware strategy, but this year, after trading away Fielder and shifting Cabrera back to first, the defense is starting to fall into place. Castellanos is a significant upgrade over Cabrera, Cabrera is an upgrade over Fielder, Kinsler is probably a wash with Infante. Shortstop is confusing, because Iglesisas was awesome, but only played for two months and Peralta was good at certain things, not to mention Alex Gonzalez being around for a couple weeks this year.

This offseason, I suggested the new defense (with Iglesias) would be  something like 10 to 60 runs better than last year. It’s too early to be terribly sure about that prediction (and let’s drop it down by about 5 to 10 runs), but it’s not too early to notice something very interesting. Right now, the infield has a collective UZR of about 3.5, meaning that the defense has saved three and a half runs more than the average infield. They’re at -2 DRS, but it should be noted that they’re +3 without Alex Gonzalez, which is relevant going forward.

By the popular metrics, they look much better than last year, when they were somewhere between 10 and 26 runs below average over a full season. But those runs above and below average metrics are sometimes a black box to the average fan. It’s hard to quantify “average” and a “run saved.” So let’s take a look at some very simple numbers that should tell a very simple story.

Below is a table of batting average on balls in play against (BABIP) for ground balls. The first column is league average. The second column is the Tigers.

Well, then. The Tigers were at least ten percentage points worse than average in each of the previous three years. This year, with several days of Alex Gonzalez, they’re still 11 percentage points better than average. It’s not a full season sample, but it’s close to 300 ground balls, which isn’t small potatoes.

I wouldn’t jump for joy and be certain that the Tigers are all of sudden going to be a great defensive team all season (and don’t even get me started on Torii Hunter’s extremely poor performance in RF), but it’s encouraging. Take a look at their starting pitcher ERA and FIP. The fact that they are outperforming their FIP this year after years of underperforming further supports the point.

The days of Tigers starters being slayed by the Gods of BABIP may well be coming to an end. Which is all the more reason to make sure they don’t let Porcello reach free agency.