The problem with Gundogan in our squad is that he isn't good as the sole defensive midfielder - that's not his forte. Against Arsenal, he was played at his best position - as a deeper lying sort of DM sort of AM with someone else (Fernandinho) assigned the primary DM role.
When Arsenal had possesion Gundogan dropped into DM to allow Fernandinho to drop to centre back.
He's had as many good games on average in that role as elsewhere.
For example, away to Arsenal and Spurs last season, and Chelsea at home last season.
We need to stop trying to put him in a box, one of his greatest assets to us currently is the fact you can't put him in a specific box because of his versatility/adaptability. The ideal squad player.