I think it’s a bad sign when the manager, or assistant manager in this case, starts to criticise the players publicly, it doesn’t actual sound if there’s much togetherness when that happens, I don’t mind them being honest and saying it was an awful performance but I’d rather hear them say “we are in this together, we all take responsibility and together we’ll work hard to put it right”, or words to that effect.
If the manager throws the players under the bus they aren’t going to want to play for him, they are in danger of losing the dressing room in my opinion.