Today's Fun Fact

Yesterday's post about Jose Lopez sent me rappelling deep into the recesses of his Baseball-Reference page. And by "deep" and "recesses" I mean I looked at his career home/road splits. Lopez, to date, has spent his entire statistical life in the bigs with Seattle. And, as we all know, he's a righty pull hitter, in that all of his power's to left. He isn't incapable of hitting the ball to right or up the middle, but he is incapable of hitting it hard and with distance.

So, given what we know about righty pull hitters in Safeco, we'd expect Lopez to have amassed worse numbers at home than on the road. And, indeed, that's what we see. Lopez has batted 1,756 times at home, and 1,843 times away. His home OPS is .667. His away OPS is .725. There we go, just as we suspected.

But wait! What's this? Let's look at isolated slugging percentage (SLG - BA):

Home: .134
Road: .133

And, for the league-average batter:

Home: .151
Road: .143

Additionally, according to Fangraphs, Lopez's career home-runs-per-fly-ball rate at home is 6.9%, versus 7.4% on the road. So while we see that his power took a bit of a hit in Safeco, it was pretty gentle overall in that regard. So how do we explain the worse numbers?

Here's a league-average split for BABIP - batting average on balls in play:

Home: .300
Road: .291

And here's Jose Lopez's split, spanning his career:

Home: .262
Road: .296

For the most part, Lopez's power was fine. His rate of singles, though, was cut by nearly a fifth, and that's over a sample size of like 1500 balls in play. That's an unusual park effect, and not one we'd ordinarily look out for.

I don't know what happened. He didn't hit many more infield flies. His groundball/fly ball ratio stayed the same. His line drives were down, but I'm uneasy about line drives as a stat. I can't find a satisfactory statistical explanation, and even if I could, that wouldn't identify the root cause anyway. It wouldn't tell me what it was about Safeco that caused so many more of Lopez's batted balls to end up more easily fieldable.

So it's a mystery. I guess the good news is that it isn't something we have to worry about. Most other right-handed Mariners seem to be hurt by Safeco in a more conventional way. It's just something weird for us, and something moderately encouraging for Colorado and all future Lopez employers. His power's never been great, and I doubt it ever will be, but his average should get a good deal better.