Really surprised there isn't already a list of this somewhere. I don't have the manga so I don't know which names are revealed there as opposed to the anime. I went through the scripts for the 25 episode series and could only glean the following:
In episode 14, when they do the 9 person infield move, you can see a lot of the numbers that some of the players wear, but ti's not clear enough to see any names. Center field and the 2nd basemen weren't explicitly mentioned in the anime. As for Kojima, he's usually not on the field when his team isn't on offense, instead, standing next to the manager in the dugout explaining to the manager what's going on. I'm not sure what position he plays if he was on the field.