Arsenal have not progressed since their back-to-back FA Cup wins and success this season would paper over the cracks, says Charlie Nicholas.
Arsenal face Manchester City at Wembley on Sunday in the semi-final of the FA Cup and are seeking a third win in the competition in four years.
But with their consistent top-four finishes in jeopardy, former Gunners striker Nicholas says another piece of silverware in the competition would not make up for several seasons of under-performing in the Premier League.
Asked if booking a place in the FA Cup final would silence the critics, Nicholas said: "No. Absolutely not. You look back at the two wins in two years, that feels like a long time ago.
"It gets you through with something to look forward to, to have a winning mentality and it's vital that you get that.
"There are a lot of people jealous about the consistency that Arsenal have had over the last 20 years, and it's something I've always applauded.
"But this team is getting weaker, and yet they're spending more money on it. The younger players who have now got to the age where their potential has gone, have not progressed to the stage Arsene Wenger would like.
"He can't camouflage it anymore. The fans will bite your hand off to win the FA Cup, of course they will, but it has to be a win while showing there is progress.
"Two years ago they had back-to-back FA Cup wins, and it hasn't gone forward."
Asked if an FA Cup win would cover up the cracks, Nicholas added: "I would agree. We're at a crossroads with Arsenal, and for the first time under Arsene we're saying they're not two players short, they're probably five short."
Merson disagreed, insisting: "If Arsenal beat Tottenham in the FA Cup final, the fans would write off this season.
"But Arsenal don't want to play Tottenham at the moment, not at all, and if they were to lose to Tottenham in the final, that would be it. Lights out."