It's actually NOT the official line that he was fired for not making the playoffs. That's just what was seized upon because someone poorly organized the press release. You actually have to get further down the page to get at the heart of the matter, where they specifically give the reason he was let go.
Everyone jumps on the first paragraph as an explanation for the firing. Actually, it's expository regarding the frame of reference the decisionmakers used, the lens through which they evaluated his performance, or even the reason he was asked to justify his continuation.
Ahhhh - there we get the real reason. His job results were below the expected targets, ergo, he was given the opportunity to re-interview for his job in conjunction with a comprehensive performance review. The findings showed that "the dynamics required to improve the performance of the team for the next season and beyond" were not there in the opinion/s of the decision makers. We don't know where those dynamics were off, whether it was among staff and players or staff and FO, but we know that things weren't meshing. Basically, what a thorough reading reveals is that the FO attitude about the situation is the one many here have had and the one FootyLovin expressed well intra thread. IF he had the proper relationships internally (squad, FO, whatever), then not making the playoffs would not have been a sufficient reason to send him packing.
I'm guessing they looked at decisions, interactions, and spoke with stakeholders. His meeting was a chance to hit a wonder-strike in added time. It missed. When relationships sour, it's time to move on.
Anyway, now you can and have read the same take yet again, but phrased differently. You're welcome.
'Ergo', you must have scored well on your SATs. Analysis was well-done. Hotty Toddy.