I'm calling BS on this. .52s have been in use for about a decade now. CO uses them widely for leagues and tournaments. I don't see guys having trouble fielding the ball on the infield. What I HAVE seen a lot of are guys actually able to stay in the game and continue playing after being hit with batted or thrown balls, especially pitchers. I myself have been hit in the head with a .52 ball. It hurt, but I was able to keep playing. A classic M or .44 does far more damage.
From a pitching standpoint the .52 is a much better option. It comes off the bat slower than a .44 or classic M and pitchers have time to react and possibly field the ball.
I think NSAs decision to go back to .44s is shortsighted and stupid. Apparently enough people whined that they weren't successful hitters with .52s and weren't going to play NSA anymore. That despite slowpitch bats being hotter now than they ever have been.
Playing the field and pitching, I'd rather risk a rogue hop from a .52 than a bone crushing smash with a .44.