With a player as one dimensional as James, he needs to be used as a specific role player. When playing on the counter attack, he's a good option on either flank because of his speed.
When chasing a game, he'd be a good option as a touchline hugging wide player. United have a terrible tendency of getting very narrow. When chasing a game, I'd like to see James right and Chong (not next season now obviously) left to stretch the play.
Wide players these days are expected to be pseudo number 10s. With players like James and Chong, that complicates their game too much. They haven't got the intuition or game smarts to be given free rein.
They need to keep it really simple. Stay wide, use your speed and dribbling ability, get up and down, take the full back on and put some quality into the box.