Arsene Wenger's men beat West Ham 3-1 at the Emirates Stadium on Tuesday evening but their top-four destiny remains out of their own hands after a 3-0 loss to rivals Everton earlier in April.
|8/13||Arsenal are 8/13 with Paddy Power to finish in the top four this season|
"For all the many years, the stadium they built, they've got through the last 10 years here by playing Champions League football, not really bringing in big-name stars," Merson told Sky Sports.
"So to get through that and bring in a real marquee name, [Mesut] Ozil, from Real Madrid, one of the top teams in world football, and not to get in it this year would be a disaster.
"How many years would it take to get back in? You aren't expecting Manchester United to be out of it for very long."
Arsenal reclaimed fourth place thanks to their victory over West Ham, with goals from Lukas Podolski and Olivier Giroud inspiring a comeback, but can be overtaken on Wednesday night when Everton take on Crystal Palace.