Sports

What good teams are good at

The Red Sox spent the off-season boosting their defense, mirroring the rise of statistics like Ultimate Zone Rating, which tries to measure how well defenders prevent runs.

But what stats are actually correlated with success? It turns out most World Series champions -- 72 percent of them, to be exact -- are better than average at hitting home runs. And 87 percent them are unusually good at converting balls in play into outs, as measured by defensive efficiency. But what sets champions apart, at least statistically, is their pitching: 94 percent had a below-average ERA.