Arsenal forward Alexis Sanchez cannot be a "big player" because he spends too much time sulking, former Gunners goalkeeper Jens Lehmann has said.
Chile international Sanchez has registered 22 goals and 18 assists in all competitions this season but has cut a frustrated figure during Arsenal's recent poor run.
The 28-year-old scored in the 3-1 defeat to West Brom but was seen on television cameras looking aghast after David Ospina's error allowed the home side to regain their lead.
And Lehmann, who was part of the 'Invincibles' side of 2003-04, has questioned the efforts of Sanchez, Mesut Ozil and Shkodran Mustafi during a run of four Premier League defeats in five matches.
"They talk about Sanchez being a big player but if you are sulking, you can't be a big player," he told The Sun. "You must be a big player mentally - not just be good at dribbling."
He continued: "There's always a question with Ozil - how much can he contribute when it gets tough?
"It's not Mustafi's fault someone has paid £35million for him. If someone buys me for £35m, the next day I'm not a better player.
"He is giving everything. But sometimes the team concede five, so he has to ask himself if it's good enough."
Lehmann believes Arsene Wenger's players are not doing enough to ease some of the pressure on the manager's shoulders.
"All these guys when they came to Arsenal were happy to join. They should not forget that," he said. "They can't just turn around and say, 'The manager is c**p - it's his responsibility'.
"That's not possible if you have character. They're good players, they have character - but they need to show it!
"I haven't seen Arsene criticise them. It's payback. Their next game against Manchester City is a good occasion to do that. They owe him."
The defeat at The Hawthorns saw further protests against Wenger in the away end, while planes carrying banners both in support of the under-fire manager and calling for him to leave were flown over the ground during the first half.
Lehmann was far from impressed with the scenes and says Arsenal fans should be careful when calling for the likes of Juventus boss Massimiliano Allegri to be appointed.
"The players should have tried to hit that plane with the ball, to defend their manager," he said.
"A single guy comes and holds a banner up, that's his opinion, fine. But hiring a plane? Come on, it's too much.
"The people that hold up their banners saying 'Wenger Out' don't hold up banners saying they want x, y, z to come in because this guy will guarantee success.
"Bring Allegri in and we will win everything? Who is Allegri, with all due respect? He is in Italy. Will somebody like him bring success? When you look at the type of football he is playing, it doesn't really fit Arsenal.
"None of them has a solution, someone who would guarantee them Champions League football and maybe win something."