We’re beginning to peel back the layers of metric-based evaluation. It used to be ‘high spin, throw up in the zone,’ and we found out that wasn’t always true, and that how you spin it is pretty important. Spin direction and true spin reign supreme there. Here’s an example for a fastball profile: An individual with much lower spin rate, but a spin direction closer to 12:00 — high spin efficiency/active spin — can achieve significantly higher vertical break values than an individual who generates a much higher spin rate, but a spin direction further from 12:00 — say, closer to 3:00 or 9:00 and/or less spin efficiency/active spin). We’re learning how little we know about the things thought we already had solved.