BATTING: HRs, pop-ups and hard-hit flies

It is an article of faith here at BaseballHQ.com and elsewhere that batted flyballs will leave the yard 10 per cent of the time. This is useful information, because it helps us spot batters (and pitchers) whose hr/f rates are well above or below that 10% level and expect some correction.

The theory is sound, but we might have some opportunity to fine-tune the threshold—and to add a more precise metric to our toolbox. We thought to look at the issue for a couple of reasons:

• First, gamewide data show that about 10 percent of FBs are infield flyballs (IFFBs), which by definition cannot become over-the-wall HRs. This means that batters with more pop-ups should have lower hr/f rates, and that before expecting a hr/f correction, we...

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