In my opinion, no player who is a nailed-on shit finisher could score as many as Gervinho did for Lille. IIRC his shots to goal ratio was about 4 or 5 which isn't world class especially in Ligue 1, but isn't record-breakingly bad either.
And yes, Ligue 1, crap defending, played as a proper striker, lots of 1-on-1s ... still doesn't quite explain it.
That's why I think he's got a specific form/psychology issue to work through at Arsenal. But I guess time will tell.