I think it has been Wenger's biggest flaw in the transfer market over the years, filling up with that type of player rather than addressing specific weaknesses in the team. Hence we've had periods with no top class keeper, insufficient cover at CB, no Gilberto replacement, no top notch striker etc.
Aye he's always tried the midfield overload Barcelona thing failing to realise that Barca had Pique and the like at the back.