Without knowing the rest of your roster, if there is penalty for keeping a player, etc... I would say you should probably keep them both. You'd be hard pressed to get any real improvement from moving McCoy unless you have another potential keeper you could trade for an upgrade but it sounds like Luck and McCoy are your only clear options.
Just an FYI, it helps us, as repliers, if you give more useful information in your original post. With what I see though, that is my advice. Oh, and in the off season replies are slow so be patient.