Shkodran Mustafi has been accused of failing to learn from his mistakes, with the Arsenal defender considered to be a liability by Martin Keown.
He has been a regular throughout his time at Emirates Stadium, but has also struggled to fully convince.
The current campaign has been particularly error-strewn for the 25-year-old centre-half, with costly lapses in concentration leading to criticism in a Carabao Cup final showdown with Manchester City and Premier League games against Southampton and Newcastle.
After seeing Mustafi fail to track the run of Ayoze Perez during a disappointing 2-1 defeat for Arsenal at St James' Park, Gunners legend Keown told Match of the Day 2: “It's the away form that is the worst. It's really quite appalling. It comes down to focus defensively. They have to be better.
“Mustafi seems to still be making the same mistakes he made earlier this season.
“If we look at last week against Southampton against Shane Long, a little run made to the near post and his body shape was all incorrect, he's not looking at a possible opponent and he gets done at the near post. The same thing happened again.”
Arsenal’s away form has contributed to them now being stuck in a battle for sixth spot with Premier League surprise package Burnley.
They have fared a little better on the road in continental competition, but Keown admits that struggles away from Emirates Stadium could end up costing Arsene Wenger’s side dear – both at home and abroad.
He added: “Look at the qualities you need to win away from home and if that's the Achilles heel. You need to be united, you need to have grit, determination and focus to carry out a game plan.
“They've had four wins in Europe and only three in the league. Wenger knows it's not good enough.”
Arsenal still have trips to Manchester United, Leicester and Huddersfield to take in domestically this season.
They also have a two-legged Europa League semi-final with Atletico Madrid to come, with the return date of that encounter set to take them to the Spanish capital on May 3.