Archive for July, 2015

Does Coors Field Make Rockies’ Batters Worse on the Road?

Denver is where pitchers’ peripheral numbers go to die.

Humidors and huge outfields have mitigated the issue a bit, but that’s still the first thing that comes to mind for most stat heads when the words “Coors Field” are uttered: Oh, those poor, poor pitchers.

There’s evidence, though, that the ballpark messes with hitters, too. Rockies hitters have the biggest home/road splits in baseball over the past five years … even after you correct for park effect. By weighted runs created plus, they’re 17 percent worse on the road than at home, whereas the league average home and away split is 10 percentage points lower.

In other words, Coors Field seems to giveth at home and taketh away on the road. When I asked Rockies hitters about this and checked the numbers, a clearer picture emerged: The Rockies are pitched differently at home, and their response to that difference seems to lead to problems on the road. All along, we thought pitchers were the only ones negatively affected by playing half their games at Coors Field; turns out, hitters are affected, too.

Let’s get to the root of what’s happening. First, we’ll look at how things are different at home, then explain how it’s affecting the Rockies’ performance on the road (at least those not named Nolan Arenado, who actually has more home runs and a higher OPS on the road this season).

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Batters Striking New Fear This Year

We’ve seen it happen time and time again, and the numbers agree: when a player shows power, pitchers adjust. They try to defuse that power bat by throwing fewer pitches in the zone, and fewer fastballs.

What we’d like to do here is turn the tables on this process by analyzing various hitters’ power situations based on which batters this season are seeing fewer pitches in the zone and fewer fastballs, and vice-versa.

It seems we can, and to do so we’ll use a few cool stats. The newest is Heart%, a stat created by Bill Petti that measures how often a pitch crosses the plate in the heart of the strike zone. We’ll also look at O-Swing%, which measures how often a hitter reaches at pitches outside the zone. And we’ll judge power using Isolated Slugging Percentage — slugging percentage minus batting average, or basically an extra-base hit rate.

Examining these statistics can help us identify which hitters likely have sustainable power breakouts and are worth targeting or keeping — and which fading sluggers would be best to avoid or let go.

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