The Swans sit in the bottom third of the competition after recording successive losses, with their extensive injury toll and form flagged as key reasons for the fall of last year's grand finalists.
Speaking after the 16-point loss to the Lions, Longmire said his squad haven't been able to find the right consistency and cohesion between their defensive and offensive ends.
"We can get the ball from defensive 50 into our front half, we're just not finishing. We just haven't had the consistency there," Longmire said.
"We're just getting Joel back, and he did some good things, particularly early.
"Jack, obviously his first game. We're just not finishing it off with the level of polish forward of the centre. A bit of that is going in (to the forward 50), and a bit is what our forwards are doing. It's a bit of everything."
Longmire confirmed that injured quartet Callum Mills (calf), Isaac Heeney (concussion), Logan McDonald (ankle) and Tom McCartin (concussion) all trained in Sydney on Friday, while veteran Lance Franklin (knee) is expected to return next week.
"We'd love to get a few players back," Longmire said. "Maybe Franklin next week. There'd be a few handy ones.
"A lot of them have missed a fair bit of footy. 'Ramps' (Dane Rampe) and Joel coming back in, we've had to manage them a bit up until now. We have to get that balance right.
"There's still a fair bit to play for. Get in next week and have a crack, back home and have a go again."
Cunningham's shutdown role on the All-Australian forward was a large factor in the Swans remaining in the contest until late into the game, Longmire said.
"I thought he was outstanding," the Swans coach said of his No.7.
"I've got so much respect for Charlie, he's a superstar. Harry was outstanding, it's not an easy thing to do to play on a bloke like him. It would've been a sleepless night last night for Harry, but we just thought he was outstanding.
"There were a few boys that had a real go, it's just the consistency across the board (was lacking)."
Sydney currently sits 13th on the ladder with five wins from 13 matches.