While I agree, you have to look at the circumstances as well.
Tomlin inherited what was basically a Super Bowl team, one that had a HOF QB at a young age and the top defense in the league. I give him about as much credit for his Super Bowl win as I do Switzer for his with Dallas in 1995 (see: not a whole lot).
Tomlin is like the AFC version of Mike McCarthy: a good coach, but one who has underachieved big time given the HOF QB he has had (and the Steelers overall have been far more talented over the years than the Packers). If McCarthy can get the axe mid-season despite having won 62% of his games over nearly 12 seasons, then Tomlin should be on the hot seat following a season in which they collapsed after a 7-2-1 start and missed the playoffs (assuming Baltimore does not #### the bed today). One AFCCG and ZERO Super Bowls in the last five years despite having a HOF QB, the best WR of your generation and consistently top production from whoever your starting RB is, is unforgivable. It just is.