[arrosenberg]

Sure those are two of the three true outcomes that the pitcher and hitter have the highest degree of individual control over, so how are you distinguishing that the K-rate is the issue compared to the HR%, which as you noted, is also down? From my POV the hitters optimizing for launch angle (long fly balls instead of lower-trajectory line drives) is just the other side of the equation from pitchers throwing hard and going for high K-rate.