Some thoughts i had in early March....
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I like the direct effects of the ABS challenge system. Adding a layer of strategy. Getting more calls right. And probably adding a little bit of time to the game length in order to have those things happen.
But its the secondary effects that I think are WAAAAAY more interesting and something I've been thinking about a lot. If there's an advantage to be gained players will try to gain it. If there's a new thing to be measured, people will try to measure it. Here are the big ones in my mind. I'd love to hear other thoughts and ideas on this.
1. Length of game – I think this has maybe been overstated a little. The actual time it takes to do the challenge is 10-15 seconds. We are, at most, adding like 2 minutes to game length, directly from the time it takes to perform the reviews. HOWEVER… we don’t yet know if it is the pitcher or the hitter who is going to end up with an advantage over a large sample. If the pitcher ends up with the advantage, then offense will trend down slightly, and the games will shorten. If the batters end up with the advantage, then the opposite will be true. It's hard to say which way it’ll go at this point and it might be a little bit team dependent, depending on how they allow their players to deploy the challenges
2. The strike zone – There’s a lot here. All players have been physically measured and so now they all have their own unique strike zone within the ABS system. They’ve all theoretically had unique strike zones up to this point, but that relied on the umpires to make adjustments on the fly and I suspect that they didn’t fully account for the size difference between, say, Jose Altuve and Aaron Judge. Do smaller players now get to fully realize the strikezone advantage they should’ve been getting this whole time? Does Emmanuel Rodriguez's small stature and good eye at the plate give him and even larger advantage that he's been seeing in the minor leagues up to this point? How does digging into the box affect things? It doesn’t take long into a game for there to be a hole in the batters box. Given that the strikezone will be based on the height of the plate, not the height that the player is standing at, is there an advantage to be gained by “digging in” an inch or two below the level of the plate. The new measured strike zone would go from the top of the knee, to now higher up the leg. This would help players that struggle with low strikes and have the opposite effect on players that struggle with high strikes. Will MLB regulate the amount of digging into the batters box that players are allowed to do? What about cleat length?
3. Catcher metrics – Pitch framing is no longer quite as important, but will there be a new metric of “Catcher Judgement?” I think most people agree that the catcher is in the best position to accurately judge whether a pitch was incorrectly called a ball. I’m envisioning two new measurements. A) challenge accuracy. This one is simple. How many challenges did they call for and how many of those were correct, but B) one more layer deep we will be able to analyze how many calls they SHOULD have challenged and the leverage of those pitches. You’d love to correctly challenge every missed call, but a missed 0-0 pitch that just clips the corner isn’t nearly as impactful or as big of a miss as a missed strike 3 call that caught a lot of the plate. "Catcher Judgement" feels like it's going to be a massively impactful statistic. Also, Catcher receiving position has been a hot topic the last few year. Mostly, I believe, catchers have tried to get lower behind the plate, in order to get more low strikes called. Does that matter as much any more? Will catchers go back to a more traditional crouch because it gains them back a slight advantage in throwing out runners?
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That advantage (of catcher/pitcher vs hitter) MIGHT be so stark that teams don't even really want their hitters triggering ABS challenges because of the much higher likelihood that they are wrong and they don't want their catchers to lose that ability going forward in the game. It could be that they only allow the hitters to challenge in truly extreme leverage positions, whereas, as the catchers prove out their ability to be correct a high percentage of the time, they have a much longer leash in terms of when teams allow their catchers to challenge.
Said another way... Just because, if looking back at old data, the misses that umps make tend to be more likely balls that were called strikes (calls batters would challenge), doesn't mean that those are the calls more likely to be correctly challenged. It could be that catchers would also be really good at identifying those calls, but they are, of course, not going to challenge calls that have benefitted the pitcher.