Question about trained positions and when a player is filling in for a player who's

[Chalky1989]

out of position.

If my RB is up the pitch after a storming run, and one of my CB's or perhaps my DM has come across/back to cover for him, and are effectively playing as a right back for that period of time until the RB gets back, how does the game deal with it. By this I mean, is my CB going to do a much better job of it if he's trained as a RB also, or would a CB who has attributes more suited to playing as a full back, but actually lacks the training in that position do better? I'm just curious that's all. As my RB is the marauding type, and frequently needs the RCB to cover for him. My first choice RCB isn't trained as a RB, whereas by 3rd choice CB, a 6'7 monster has training there, so I'm interested in seeing how it's managed within the game. Thanks in advance for any(constructive) answers.