There are 13 (Now 12) defensive-minded Head Coaches in the NFL:

Belicheat (hot seat)
Ryans (1st year)
Gannon (1st year)
McDermott (?)
Eberflus (hot seat)
Allen (hot seat)
Staley (fired)
Bowles (hot seat)
Tomlin (should be hot)
Carroll
Vrabel (hot seat)
Rivera (hot seat)
Saleh (hot seat)

Out of these 13, there are 2 teams that MIGHT make the playoffs - the Texans and the Bills. All of the top teams have an offensive-minded Head Coach. I hope the Steelers' next hire is an offensive guy.