Apples and Oranges, for two reasons
One United were champions in Fergie’s last season and we finished 6th having lost seven away games in a row. We had a central midfield of Xhaka and Elneny and creative players like Iwobi and Mkyhtarian it’s fair to say we weren’t in the best state when Wenger left us so not really buying into the argument that he left us with a decent squad either.
Second Ferguson retired at a time of his own choosing, Wenger would still be here today if the decision had been left with him. So in a way that excuses Wenger a bit more, where as I genuinely think Ferguson almost intentionally set United up to fail with a lackadaisical succession plan…he wanted Moyes because he knew Moyes wouldn’t outshine him. Someone like Ferguson is small minded and petty like that where as Wenger even if he’d left of his own volition I think he would have maybe laid the groundwork for someone to take over but I don’t think he would have tried to influence who his replacement was.