We weren't, the 3 bottom teams were already dead, this year the 4 teams between us and relegation are all capable of going on a run of a few games. The other factor is we had a genuine chance at Europa (which got us back into Europe this year), we were bookies favorites to win with United. That's not even taking into account Ange had shown he could get the team to 5th the season before, and we were capable (not consistently) of playing winning football (Frank hasn't)
These are all risk/reward decisions, it may seem like small margins but our situation this season is notably worse than last, by this time we had players coming back from the injuries, the league was "safe", the manager was in 2nd year, fans hadn't turned, each adds up.
Personally I think Levy should have fired Ange in December, but he made a calculated risk call and it paid off, what is the pay off for sticking with Frank? (we aren't going to get to even CL SF), that's where I think he would have pulled trigger.