Moyes. No question. He could be wasteful with cash (Bilyaletdinov, Beattie, Krolrdup) but he couldn't be anymore disastrous than Koeman. Koeman has paid tens of millions on rubbish like Williams, Bolasie, Klaassen, overpaid on bang average players like Schneiderlin, paid out £15M more than he should have chasing the signature of Sigurdsson, and he's paid needless millions for players who have been loaned out straight away and millions on a player like Lookman who he wont now play.
In my estimation he's wasted roughly £90M-£100M of the circa £200M he's spent since being here.
I said about half way through the summer window that the profligate level of spending under this feller would be looked back upon as a disastrous period in the club's history.
https://www.grandoldteam.com/forum/threads/koeman-weve-only-spent-£7m.98174/page-39#post-5669233
I see no reason to reassess that prediction. He's been a complete calamity in the transfer market.