The Gunners have now lost their last four in all competitions with large sections of the visiting support chanting for Wenger to leave yesterday.
Arsenal are often criticised for a lack of leaders, fight and desire in the playing squad.
Sidwell, who started his career at Arsenal and is currently out with an ankle injury, says that is the case with Wenger's side.
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We knew from the off, if we had a good start and played on the front foot and got after them, we would have a chance
"It is what everyone has been saying of late - there are no characters, no fight, no desire, no passion to wear the shirt and that was evident yesterday," Brighton star Sidwell told talkSPORT.
"Before the game I saw them in the tunnel and their body language wasn't that of a team that was ready to roll their sleeves up and give it a go.
"We knew from the off, if we had a good start and played on the front foot and got after them, we would have a chance.
"Back in the day, you knew you were going to be in for a tough game (against Arsenal).
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“You knew they could play free-flowing football but you would also physically be in for a tough game. Now that toughness is gone.
"All it seems they have got is their flair and technical ability - and that has even gone now.
"Their confidence is shot to pieces."