Let's not go too far the other way. Clearly I don't know the inner workings of what happened over the past 18 months but I wouldn't throw the baby out with the bathwater with Walsh. He has immense knowledge of the English game and he wouldn't be the first person to not get along with Koeman, Les Reed had his differences too by all accounts.
His signings of Pickford, Gueye, Onyekuru and Sandro haven't been bad at all (Sandro was low risk for the fee and has got to be better than his confidence-shot performances so far) and he's re-organised the scouting setup since he's been appointed.
Clearly he's partly culpable for the lack of a striker and centre half but we don't know if his suggestions were discounted by Koeman, I'd be amazed if he offered nothing by the way of options for those two positions.
If he's on the selection panel for the next manager we should be able to appoint someone he feels he can work with, which is half the battle in these type of dynamics.
I would be very suprised it Moshiri laid all the blame at Koeman's feet, so I would imagine Walsh is skating on pretty thin ice right now.