#2 Defensive basics failing Mustafi
Whether it's positioning or shielding, Mustafi is failing in the basics of defending for Arsenal. Leading up to Palace's first goal in the 17th minute, Carl Jenkinson failed to play Christian Benteke offside, but it was Mustafi who let the Belgian have a free run near the goal mouth. The result? Benteke scored his first goal in about 20 Premier League games.
In the second half, the advantage was with Arsenal when Mesut Ozil struck the equaliser. The Gunners were riding the momentum and looked to snatch the lead from Palace but it was undone by Mustafi.
Mustafi presumed that Bernd Leno would charge out and collect the flick-on by Benteke that was played for Wilfried Zaha. He looked at his goalkeeper and forgot for a moment that he was shielding the ball from Zaha. Just a second later, Zaha shrugged off Mustafi and slotted the ball past Leno for Palace's second in the 61st minute.
It wasn't just this game alone. This is a pattern that's on display every time Mustafi is defending for Arsenal. Mustafi is constantly losing focus during key moments for Arsenal and that's costing them dear.
Former Arsenal defender Martin Keown, a TV Pundit now, held Mustafi responsible even for the third goal scored by James McArthur for Palace, claiming Mustafi got attracted to the ball instead of tracking the man.
After the Palace defeat, Emery defended his defender by saying Mustafi has been consistent throughout the season. Consistenly bad? Yes.
Moreover, Mustafi isn't one of the fastest players who can track back whenever a pacey forward is wreaking havoc at the Arsenal half. He also dives into those pointless sliding challenges, giving away needless free-kicks in dangerous areas.
Tackling, aerial duels and shielding are his biggest strengths but even those are letting him down, which is another reason why Arsenal should consider selling him with over two years left in his contract.