There are many differences between Mike Tomlin and Bill Cowher, just as there are many differences between Kevin Colbert and Tom Donahoe.

But there is one point of football philosophy that unites all four men:

• Belief in a deep bullpen at the quarterback position

Given how important the quarterback position is, keeping an accomplished backup might seem like a no brainer. But its not, as Indianapolis’ experience when Peyton Manning went down demonstrates.

Since 1992 the Steelers have gone to great pains to insure themselves against such a calamity.

• During Cowher’s rookie year, it was Neil O’Donnell and Bubby Brister
• Mike Tomazck played the role of the veteran back up from ’93 to ‘99

There were even two season (1995 and 1999) during the Cowher-Donahoe years when the Steelers carried four quarterbacks on their active roster.

When Kevin Colbert arrived in 2000, one of the first things he did was to convince Bill Cowher to go with a QB number 2 who offered at a true value add.

Kent Graham was the first such quarterback, and while he didn’t work out to well, the Steelers added Tommy Maddox in 2001 and wasted little time in snapping up Charlie Batch in 2002.

Mike Tomlin has embraced that philosophy as well. When Charlie Batch broke is collarbone during 2008 training camp, Tomlin wasted no time in bringing Byron Leftwich to Pittsburgh, just as he immediately turned to Leftwich  when Ben Roethlisberger’s legal troubles led to his four game suspension.

The Steelers of course weathered that suspension well, despite the fact that 5 quarters into the season they were playing their fifth string quarterback.

• So the Steelers philosophy of investing in depth at quarterback has served them well.

But that philosophy is about to undergo it’s most severe test.

Steelers Face Life without Roethlisberger

There’s a certain irony to Ben Roethlsiberger’s injury vs. the Chiefs.

• Todd Haley was brought in to keep Ben Roethlisberger upright
• The offensive line had finally begun to improve its pass protection

Yet, Ben Roethlisberger’s number still came up. Yes, the Steelers have prepared for such an eventuality, but this eventuality happens to come when the Steelers have to play the Baltimore Ravens 2 times in 3 weeks.

It is during these three weeks that the Steelers will define their playoff future.

• Can Byron Leftwich hold the down the fort? 
• Can Todd Haley adjust his short-passing offense to accommodate Leftwich’s Saturn V strength arm?
• Can the offensive line return to the dominance it flashed just a few weeks ago?

Mike Tomlin has always lived by the philosophy of  “The Standard is the Standard” or  “Next Man Up” or what have you. What it all boils down to is that Tomlin allows no daylight in which injuries can become excuses.

When the Steelers 2012 season began, Steel Curtain Rising looked at the large number of injuries plaguing Pittsburgh and suggested that Tomlin’s philosophy would undergo its stiffest test yet.

The test is about to get even stiffer.