I have got a hypothesis with a tiny bit of science behind it.
Given Butler (probably with input from Turnbull) wants to keep 18 or so of last seasons squad to spearhead next seasons title tilt then he doesn’t think the players are the reason we did not achieve it last season.
By inference he thinks the 3 management that have recently departed the club were the problem. He couldn’t/wouldn’t admit this publicly of course but it is a fairly obvious conclusion to draw.