New manager bounce and players wanting to impress Koeman but that never lasts. I think a couple of players have figured out they're now past it (the Chelsea game was the beginning of the end for a few). I also think that Chelsea game knocked the confidence out of them too.
Agreed, some need to be moved on but my concern is that the manager himself needs to address his own flaws before he sees results on the pitch with new and exiting players.