The Gunners were beaten 1-0 at the Etihad Stadium as Raheem Sterling’s first-half goal was enough to secure victory for Pep Guardiola’s side.
Arteta opted to start with a 3-4-3 with David Luiz, Gabriel Magalhaes and Kieran Tierney playing in a three-man defence.
Bellerin, meanwhile, played on the right flank but rarely got the opportunity to press forward as City dominated possession.
And Adams believes now is the time for Arteta to decide on a centre-back partner for Gabriel and move to a traditional four-man defence.
‘I think it’s time for a back four. I’ve been saying it since the start of the season,’ Adams told Premier League Productions.
‘It wins you cup games, it doesn’t win you league titles. If he wants to build for the future.
‘I think he’s got problems with Hector, I think his defending today wasn’t very good at all.
‘But I’d like him to go to a back four. They’ve got Gabriel now, get him a partnership.
‘They’ve been unlucky at the start with Holding going down but get them into a back four.
‘They look like they’ve a holding midfielder now who’s got a bit of presence and build for the future.’
‘Arsenal have pressed them and they’ve played around the press very well,’ said the former Arsenal captain.
‘Hector Bellerin again, and the goalkeeper, I always look at it defensively.
‘Man City were too good, they passed it around, he [Phil Foden] steps inside Hector too easy. The goalkeeper is pushing it into the danger zone, you’ve got to push it away out of the danger zone, and he’s [Sterling] had a tap-in, which is disappointing.’