An interesting point was raised by Le Grove (not a fan of his myself) He suggested Gazidis went over Wenger's head in signing Welbeck, he deduced this from the fact Wenger hasn't commented on Welbeck transfer.
I'm pretty sure if that were true Wenger would resign.
Somebody else also said that Wenger wanted to sign Welbeck on loan but the board preferred a permanent deal and insisted on that