The best games he plays for us are always against teams who don't counter us much (Burnley, even RM where we played more conservativey).
Against pacy counter attacking sides he has struggled from the off and I'm not sure where the improvement can come from, you can't just change the way a player plays.
He reminds me of Matic, Matic was excellent for counter attacking sides like Jose's Chelsea but put him in a team where he has to defend against pace and he has struggled.
I would ask questions from our recruitment people. Surely someone must've seen these potential issues. Probably he was again some option C or D (after De Jong, Jorginho at least) and we had to settle for someone where we hoped it worked, not expected it to work.