The Steelers signed 2008 NFL Defensive Player of the Year James Harrison to a six-year, $51.75 million contract on Monday, replacing a contract that would have paid Harrison $1.4 million in 2009.

The contract is a nice one for Harrison, a 31-year old OLB, and certainly not as ridiculous as handing a 320-pound (or more) defensive tackle with penchant for stomping on people’s faces with his cleats and possibly taking non-contract seasons off a record breaking $100+ million deal.

But, looking back at the Steelers history, one has to wonder if the extension for Harrison is sign of a new philosophy in Pittsburgh, in theory being driven by coach Mike Tomlin, who has a reputation as being more of a “Player’s Coach” than Bill Cowher or Chuck Noll ever were.

In the past, Pittsburgh has let several big name LBs leave in the middle of what would be considered my many their prime, or at the very worst just past their prime–seemingly always considering the system more important than the player.

Hardy Nickerson was just 27 years old and a six-year veteran when the Steelers let him leave for Tampa Bay, where he starred for 8 seasons, before finishing off with a couple years in Jacksonville and one in Green Bay.

Kevin Greene, who came into the league with the Rams, played for just three seasons with the Steelers from 1993-1995, but racked up 35.5 sakcs and a first team All-Pro election, before being allowed to move on to Carolina, where he posted 14.5 more sacks in his first season with the Panthers (and added 37.5 more in three seasons with the Panthers and 49ers after that).

Levon Kirkland left at age 31, after 9 years with the Steelers during which he was considered to be amongst the best ILB in the game–and in possibly the greatest indication that it was the system more than the player, only lasted two more years in the league (although his weight was a large part of that).

And most recently, Joey Porter was allowed to leave, after eight seasons with the club, which included 60 sacks, 3 Pro Bowls and an All-Pro season.  Of course, Porter also caused his fair share of headaches, and was given a large contract to join the Miami Dolphins–a contract which appeared to support the Steelers stance of system over player in the first year (just 5.5 sacks), but was justified in a resurgent 2008 (NFL leading 17.5 sacks).

So why now are the Steelers shelling out big bucks for a LB who is 31-years old?  Granted, he didn’t play a lot his first few seasons, so he doesn’t have the same wear and tear as other 31-year old LBs–but he also doesn’t have the same track record as many of the guys who were allowed to walk before him.

Only time will tell if the Steelers are staying one step ahead of the curve with this signing, or if they are taking the first step in the other direction…