Where the Astros have been at their best

By Jeff Sullivan

It was almost cute when it started — there were the Astros, playing really competitive baseball, a year or two ahead of schedule. They stormed out of the gate and people everywhere wrote about the possibility of the Astros making the playoffs without really believing it would happen. And to this point the Astros still haven’t clinched a berth in the playoffs, but with every passing day, they’ve been taken a little more seriously. They’ll be in first place at the halfway mark, leaving only another half left to go, and the prospect promotion is well underway. It’s not so cute these days. It’s like the Astros have skipped a step.

Look over what they’ve accomplished and you can understand why the Astros are a legitimate threat to make a playoff run. Hitting-wise, they’ve collectively been above-average. The rotation might not have a classic ace, but it’s been above-average as a group. The bullpen, too, has been above-average, and the team’s been good about running the bases, and on top of all that, the Astros have avoided ugly black holes. You’d be hard-pressed to find a problem spot, which is a feature of a winning club. But what might you call the Astros’ strength? Some might suggest hitting for power, which, yeah, they’re good at that. But they’re even better at dealing with groundballs.

And that’s not the easiest thing to notice. Especially since the Astros aren’t running out a defensive infield with a couple of Andrelton Simmonses. On a game-to-game basis, you might not pick up the subtleties, but if the subtleties keep adding on to one another, eventually a big difference can be observed. And in the numbers, we can observe a big difference. It’s easy to isolate groundballs. Groundballs tend to be the responsibility of the infield. Whatever the Astros have been doing has been working.

Overall, the league’s pitchers have allowed a .266 slugging percentage on grounders. Sometimes people will just look at batting average allowed, but that doesn’t capture the occasional double or triple down the line. In any case, grounders aren’t super productive, but there’s still a range we can see. Here are the pitching staffs that have allowed the lowest slugging percentages on grounders:

It’s the Astros by a relative mile, as the difference between first and second place is the difference between second and tenth place. The separation between the Astros and the Blue Jays is 19 total bases. The separation between the Astros and the league average is 49 total bases. The Astros, see, have already generated just over 1,000 grounders on the season.

Here are the top teams against grounders hit by righties:

Here are the top teams against grounders hit by lefties:

Doesn’t matter which way you slice it — the Astros lead against hitters on both sides. Curious, I messed around with some spray-chart information. With right-handed groundballs, the Astros have caused a higher-than-average rate of them to go to the opposite half of the field. With left-handed groundballs, the Astros have caused a higher-than-average rate of them to go to the pull half of the field. So, they’re generating grounders between first and second, and those are pretty playable grounders, but that doesn’t just answer everything. It’s simply a bundle of potentially-useful facts.

Because it’s 2015, we can try to use some newer data in attempting to explain what we see. The Astros have allowed baseball’s lowest hard-hit rate. According to Baseball Savant and Statcast, Astros pitchers have allowed the third-lowest average groundball exit velocity. But then, the White Sox have allowed the very lowest average groundball exit velocity, and in terms of slugging percentage allowed on grounders, they’re last in the majors. So that might not tell us a whole lot, either.

Forget trying to explain things for a moment. We can take this beyond this season. The Astros, right now, lead baseball with that .218 slugging percentage allowed on grounders. This is uncommon territory for a team. In 2004, the Cardinals finished at .213 allowed. The next year, the A’s matched that. And then in 2010, the A’s finished at .221. Those are the top teams, going back to 2003, according to Baseball-Reference. This year’s Astros would be right in there, were the season complete.

Conveniently, over at StatCorner, Matthew Carruth tries to assign run values to this. He grades every team on its groundball performance, making the assumption that, over large samples, the grounder distributions even out. That’s a presumably inaccurate assumption so everything you see is an estimate, but you can still get an idea of the value. Here would be the top teams going back to 2007, by runs above average handling grounders:

This year’s Astros show up, despite a season that’s half complete. They, of course, lead all of baseball by a good margin in 2015. If they were to continue ahead at the same pace, they’d finish at +67 runs. If they were to slow down by half, then they’d finish at +50 runs, which would still put them in the top five. This has been a major contributor, and for the Astros as an organization, it’s been building. Their team performance on grounders since 2007:

Last year was the first positive year since 2008. Now they’re poised to blow last year away. In this respect, and in many other respects. They’re looking at what’s already an 18-run improvement, with three months of baseball to play.

The pitchers and the infielders are working well together. And when you look around the infield, you don’t see many names of guys considered standout defensive talents. Carlos Correa is good, but he hasn’t been up all that long. Before him, the shortstops were Marwin Gonzalez, Jonathan Villar, and Jed Lowrie. Luis Valbuena is considered neither good nor bad. Jose Altuve doesn’t have the greatest defensive reputation. Chris Carter seems like a fairly mediocre defensive first baseman. And actually, by UZR, the Astros infield this year has been below-average. But UZR doesn’t handle the shift very well. The Astros love them some shifts. Even the pitchers have come all the way around. Plenty of teams shift, but no team is more aggressive than the Astros are, and I’m guessing that’s a big part of what we’re seeing. Pitchers are better at pitching to shifts, defenders are better at succeeding in shifts, and maybe the shifts themselves have gotten better.

The way I figure, the Astros have been able to maximize the defensive ability of their infield. That’s always the point with any shift, but maybe the Astros are just the best team at it, and maybe Dallas Keuchel in particular is an excellent pitcher to work behind. On his grounders, opponents have slugged just .146. And he mostly allows grounders. Combine a groundball pitcher with good command and a strategically-placed infield and you get a guy who comes away looking like one of the best starting pitchers in the game. Some of this, I’m sure, is just noise, but I don’t think Keuchel could’ve been placed in a better system.

The Astros, as a team, have generated one of the highest rates of grounders in baseball. The Astros, as a team, have been baseball’s best at fielding those grounders and turning them into outs. That’s a very quiet way to vault yourself toward the top of a division. Don’t get me wrong, the Astros have been doing a number of things right. They just haven’t done other things this right.

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