Well, that is a mystery. It's possible Dan is in error. If so, I'm sure he'd like to correct it.
I speculate that it's possible to measure a different value. First, it may include key travel. Second, a given program may choose to sit on an input for more than one frame (perhaps he picked a "bad" game for this test). Anyway, I highly suggest reaching out to him, because I agree this is an interesting discrepancy.
