I hate what I call "ungrateful" sackings: on an old version of FM I managed to win two out of three league titles with Everton, and the following season was sacked while sitting in fourth at Christmas. Very annoying. I took over at Sunderland and signed my old players on free transfers, won the league again, which was satisfying.
This also happened on FM12, I managed two consecutive Champions League qualifications with Sporting Gijon, then spent a summer rebuilding the squad. Some setbacks meant that I was lying in 10th in February, but still in reach of Europe; however I was unceremoniously sacked.
This is sometimes one of the reasons why I don't like taking on long saves with one team; if you try to do something different one season, instead of just playing with the same tactic and using the same formula every time, you can get sacked. These days when I need to change things around I usually move to a new team in the same game.