YEs, Arte has to accept some of the blame for that trade.
I have to assume that Reagins was the driving force behind the trade since if he had opposed the trade he would probably still be the GM.
I think Arte realized that Reagins was over his head in negotiating with other GM's and that is why he is no longer in the position.
As far as Wells, I've rooted for him since he became an Angel and will continue to root for him to do well and contribute to the Angels success.