I can't help but think it was a correction of a previous error. Anyone who knows anything about OOTP and looks at
Connor Joe's 2022 statline couldn't possibly have pegged him as starting the year as a 78. He's a 1B/Corner OFer with, at that time, a sub 100 OPS+. How in the world could he possibly be rated a 78? It doesn't make sense. Him being rated a 70, after the update however, does. I haven't done an analysis of all the players like some probably have, but my guess is if someone looked back at the ones we're surprised by that most, if not all, of those players were probably over-rated from the start.
Ultimately, I think it's best to try not to take all this too seriously. It's unfortunate for those of us who like to predict how ratings will change as who knows what will happen next, but we have to keep in mind that whoever is coming up with the ratings is human and as such they'll have biases and make mistakes. This isn't a real stock market with billions of dollars at stake, it's just a silly little game only loosely based on baseball.