The reigning Premier League champions have at times this campaign converted to a trio at the back with manager Roberto Mancini using it as a back-up plan and even though some of the squad weren't happy with it, Barry insists it must be a respected plan if the boss wants to use it.
"I missed the whole pre-season with my operation," Barry told the Manchester Evening News.
"The lads said they worked on three at the back, as the manager wanted it as a Plan B.
"The players didn't seem to be overly-confident playing it.
"If the manager wants to go with it you have to do your best and respect it."