Not sure why anybody would want to remove Cowher's SB winning season from his playoff record. I suppose it would be to try to show that 1 year was a fluke and he sucked otherwise.
The exact opposite is true. Cowher was a great playoff coach
Bill Cowher - 15 seasons 1992 - 2006
Playoffs in 10 of 15 years
Playoff record 12-9 (57%)
Super Bowl Wins 1
Super Bowl Loss 1
AFC Champ appearances (other than SB years) 4
One and Done playoff seasons 2
Cowher went 1 and done in his first 2 seasons as coach. He NEVER went 1 and done again in his other 8 playoff seasons
Cowher's Playoff Record by QB
O'Donnell 3-4 , including 1 AFCC and 1 SB appearance, made playofs all 4 seasons as starter
Tomczak 1-1 in same season
Kordell 2-2 in 2 playoff seasons (1-1 each) reached AFCC twice
Maddox 1-1 in same season
Big Ben 5-1 in 2 playoff seasons 1 AFCC loss. 1 SB win
It is clear that Cowher got the steelers to overachieve most seasons. He made it to the AFC Champ twice with Kordell. He nearly beat the dynasty Cowboys with O'Donnell
Mike Tomlin Playoff record - All with Big Ben
12 seasons 2007 - 2018
Playoffs in 8 of 12 seasons
Playoff Record 8-7 (53%)
Super Bowl Wins 1
Super Bowl Loss 1
AFC Champ appearance (other than SB years) 1
One and Done playoff seasons 4
Cowher's playoff record is far more impressive. A few points
O'Donnell started 4 years, went 1 and done in playoffs the first 2, then he went to an AFCC and a SB the next 2. He then became a free agent and signed a huge deal with the Jets. The Steelers had to find a new QB and it set them back.
O'Donnel wasn't great but he was pretty good and a good fit with the steelers. If he hadn't left, steelers possibly win a SB with him
Another key point is that the old AFC Central was a much tougher division that the current AFC North.
The AFC Central had 5 teams for 4 seasons (8 div games) and 6 teams for 3 seasons (10 freaking division games)
AFC Central - Pitt, Cleve, Cinn, Balt, Tenn, Jax
The Jags were damn good for stretches and the games with the Titans were always battles, that was on top of the other division games.
Cowher went 13-3 and made an AFC Champ game, losing to the Elway, Terrell Davis team that cheated the salary cap to be so strong.