Arsenal have also had players shown red cards in games against Manchester City and Liverpool this term, and Sinclair feels Arteta's demeanour on the touchline is affecting his team's decision-making in key moments.
"I struggle to be able to defend how they've gone into that game," Sinclair told talkSPORT.
"Six red cards this season – Gabriel, Xhaka, Martinelli, Holding – the list goes on. Every time they go into a big game, they have head loss.
"For me, it's not one individual player, it has to come from the manager. He's agitated, he's animated on the side."
Sinclair claimed that Arsenal must learn to control their emotions better when coming up against top opposition.
He also said: "His comments after the game, he's almost trying to give his team excuses. Don't give the team excuses.
"They've got to be better, they've got to be more controlled, they've got to be more disciplined in big games like that.
"At the moment, they're not getting it, and the reason they're not getting it, for me, it's coming from the leader."
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!