Late in the 2nd half, he played a pass to Rashford on the left, and it was clear as day Rashford was going to knock it on back to him for him to run on to, but instead Darmian just turned and ran back to his own half whilst Rashford looked on bemusedly. That one moment epitomised him entirely. I can't remember a less attacking fullback at this level. Even if Mourinho supposedly wants one of his fullbacks to be more defensive, surely you can take a risk now and again when space opens up to attack, and at that moment they were caught short with acres of space for Darmian to chase Rashford's one-two. Maddening. It looks like Rashford gave him a bollocking for not following up as well.
He made two or three good challenges, but he looks terrified of being anywhere near the ball.