Mikel Arteta has said there were internal divisions that undermined Arsenal's season and added that "some people inside" the club have tried to "hurt" the team.
Arsenal could yet qualify for next year's inaugural Europa Conference League if they beat Brighton in their final Premier League match on Sunday and other results go their way.
It would provide a positive end to a difficult campaign during which Arteta said that he was searching for a mole leaking negative information from the club.
Three fringe players subsequently agreed contract terminations in January -- Mesut Ozil, Sokratis Papastathopoulos and Shkodran Mustafi - with Sead Kolasinac among a number of others going out on loan.
When asked what the best thing about this season had been at a news conference on Friday, Arteta replied: "The best thing has been to keep a team, a staff, employees and everybody together. In those circumstances when you are not winning and when there are so many people, some inside and some outside that are trying to hurt.
"And to keep them together and block that and be so strong, I think that is some achievement. As normally when that happens, that cracks and everything falls and it didn't."
Pushed on whether the "people inside" were still at the club, Arteta replied: "No."
Arsenal are expected to sell several first-team players this summer while owners Kroenke Sports Enterprises have vowed to invest funds to help rebuild the squad.
Arteta is keen for the club's summer business to be conducted quickly but he cast doubt over that possibility, not least because of European Championship starting on June 11.
"That would be ideal to do everything as early as possible and have all the players who know they will continue here on the first day of preseason but it's not going to happen," he said.
"We have the Euros and everything is going to be delayed. There are many things to be done that will take time. But we know how key it will be and what we don't want is what happened last year."