I agree that "rule changes" mid-season aren't the best idea. That being said, this is just a rule that they've decided to actually enforce now that people aren't just using rosin and spit, but they're using advanced adhesives to not just help them grip the ball, but to put ridiculous spin and movement on the ball. The other thing is, Glasnow says a lot of hitters have no problem with pitchers using rosin and sunscreen, but in the middle of a game, I do wonder how many of these substances are similar in tack and appearance. It shouldn't be up to an umpire to decide if something is benign (sunscreen) or not. If you're putting something on the ball, the rules are what they are. It's possible if the union comes forward strongly enough, they'll find a decent middle ground. Maybe that happens. We'll see, I guess.