You need to allow the user to add a position to the player !  It’s not realistic to have a player (let’s just use Mookie Betts as an example) who has played SS and 2B most of the season not be able to be placed into that role.  There are many more examples that can be given - the best fix would to allow the user to select up to 2 additional positions for the player, this would also allow to place the utility players in the correct position for that game.  Also allow the user to pick the line up for each game, this will allow for lefty vs righty players to be put into the lineup when the opponents picture is left or right thrower.  Lastly, you need to allow for expansion of the rooster of each team, the reserve player should be expanded to allow for more substations during a game