I just wanted to say I'm really enjoying the tech test the past few days and previous games in the series as well. As a former player I had a few thoughts that might really add to the authenticity of the game.
I think having more sounds in game like the interaction between players would really make for a more realistic game. If you have a pitcher that's struggling let's have the catcher saying encouraging stuff like, "settle down here, we'll get him right here or something like you and me", to get the pitcher to settle down. I played with multiple organizations in my career and as a pitcher had a ton of different catchers. But I didn't perform as well with some catchers versus others, for example I played with Kurt Suzuki in Oakland and he was probably the best catcher I had in my career. He always knew how to settle me down when I struggled with location. This can be an attribute that's added in game.
The same can be said for the position players, have them chatting more in the field of play. If there is a man on 1st with less than two outs show the pitcher indicating to the SS that he's turning two with him if the ball is hit straight to the pitcher. Also have the infield shouting out how many outs there are, pumping the pitcher up when making quick outs or encouraging him if he's struggling a bit. You don't want it to be overly chatty because that's not realistic at the professional level but people are talking throughout the game. All these things can be attributes that can be added and modify for each player that can really add to the realism of an already great game.