That's just rumours. Moshiri sacked him, it was one of the first things he did when he got here!
I would say he cant be that stupid but...
I actually like Martinez but never go back, it didn't work out for our best ever manager, so it wont work for someone like Martinez (or Moyes for that matter)
Martinez was just so stubborn. Has a plan A but doesnt divert from it. The best managers change their approach regularly if it isnt working. Mourinho was a master of it. Klopp will do it, Pep less so because plan A works so often. It odesnt mean change and become hoofball, but just tweaks throughout the midfield and how they set up.
It's all well and good having plan A being all pretty and smooth, but when that doesnt work, what is in your back pocket? He either had nothing, or was so stubborn to stick to the key principles that didnt work.
Which is a massive shame as he seems a genuinely decent man, which are few and far between in football, and I wanted him to be a real success.