He was a completely terrible manager here and he wasn't good for Napoli either. The game is past him and I for one congratulate Simeone on back to back La Liga victories in advance of next season.
I'm sorry mate, but this is a wild exaggeration. He finished 2nd with Napoli and he inherited a team in 18th here, showed form that was 8th in the league for the remainder of that season, and the following season improved the points total to 59 points, the highest in 4 years.
Was the style of play by which he did this attractive? Probably not. Can you argue we were fortunate in games, and as a whole? Again yes you can make that argument. Was it achieved with a short termism that was unsustainable? Again potentially so.
Have we some grounds for feeling angry with how he left? Yes I would say there is some legitimacy.
However was his performance "completely terrible"? I can only view this as counter factual I'm afraid.
I also think, we are only going to make the next managers job harder if we assume 59 point is some awful failure for us. It creates an unrealistic set of expectations and the cycle continues.