That is the verdict of Tottenham legend Tim Sherwood.
New manager Unai Emery was handed a baptism of fire as his side kicked off the season with losses to Manchester City and Chelsea.
But after a shaky start to the season, the Gunners have recovered well to climb back up to fifth place thanks to an unbeaten run of nine league games.
Question marks have lingered over the solidity of the Arsenal back line with several defenders spending time on the sidelines.
“I think the game changer might be Koscielny getting fit”
No current player has spent longer in the Gunners injury room than club captain Koscielny though, with the centre-back having now been injured for over six months with an Achilles problem.
And former England midfielder Sherwood believes the Frenchman’s return could see a change in fortunes at the Emirates come the end of the season.
“I think the game changer might be Koscielny getting fit,” Sherwood told Saturday Morning Savage.
“He’s a game changer for Arsenal because at the moment I still think they’re weak at the back.”
Arsenal news: Emery needs a fully fit Laurent Koscielny back in his team, according to Sherwood (Pic: GETTY)
Arsenal news: Koscielny was injured in last season’s Europa League semi-finals (Pic: GETTY)
Arsenal impressed many by holding title chasers Liverpool to a 1-1 draw last Saturday.
And Premier League winner Sherwood believes the north London side need to continue perform consistently against the league’s biggest sides if they are to challenge for Champions League football once again.
“The game against Liverpool was fantastic, and they played Chelsea early on in the season and got beat heavily, (played) Man City got beat.
“From then on they’ve not really played any of the top teams.
“But last week they go and play Liverpool and they performed very, very well.”
Arsenal have seen a revival in attack with Pierre-Emerick Aubameyang and Alexandre Lacazette forming a formidable strike partnership.
And while Sherwood acknowledges they now have “unbelievable firepower”, he insists if Arsenal are to press for a top-four finish, they will need a fully fit Koscielny at the heart of their defence.
“They’ve got the firepower, they’ve got unbelievable firepower now, they’ve got goals all over the pitch,” he said.
Arsenal news: Koscielny has returned to training following his horrific injury (Pic: GETTY)
“But I think Koscielny will be a game changer, if he comes back fit I think he can be the difference and give them a chance for the top four.
“But I just think they’ll fall short.”
Arsenal return to Premier League action tomorrow when they host Wolves (4:30pm).