The 26-year old signed for the Gunners from Lyon in a club-record move on Wednesday, but he still remains behind Giroud in the France pecking order.
"Well look if you're an Arsenal fan most likely you wanted the club to spend money," Marcotti said on ESPN FC.
"This deal would smash their transfer record, if you throw in the add-ons it's around £52million, nearly £10million more than they paid for Mesut Ozil a few years ago.
"It does put a big question mark over Olivier Giroud and frankly to what degree Lacazette is better than Giroud.
"Certainly Didier Deschamps the France manager doesn't seem to think so.
"You assume that he fits what Wenger wants to do better."