Signing Polamalu is not as simple and clear cut as many will see it.
While he is obviously the most important piece of the Steelers defense, and arguably of the whole roster, he has had his durability concerns over the past few years.
Polamalu has missed 18 starts in the past four years during the regular season, and while he has appeared in every playoff game, he was obviously hampered by his Achilles problem last year. Polamalu is 30 years of age and has appeared to be fully healthy during the preseason, but the Steelers are already taking precautions with him.
Any contract that any team gives to a player is a risk, as the Indianapolis Colts are finding out. The previously ever-present Peyton Manning's career could be over before playing under the contract he signed in the offseason.
Polamalu should be receiving a similar deal to Manning, as he is, at worst, the second-best at his position in the league.
Ideally, the team would have allowed Polamalu to prove himself this season, before, at worst, the franchise tagging him after the season, but there are a lot of positive reasons to locking him up before the season started.
The one negative—if Polamalu's health doesn't hold up once again—is outweighed by Polamalu's importance to the defense. Without him, the Steelers won't be competing for any Super Bowl in the near future.
At worst, Polamalu never completes an NFL season again and he becomes dead weight on the cap. However, even if that still happens, it makes no difference because the team's defense is a veteran group that won't be able to adjust to him being released easily.
So even if Polamalu is holding down some cap space on the sidelines, it's worth having him under contract because the defense wouldn't be the best in the league without him anyway.
The reward is huge, obviously, as Polamalu won the defensive player of the year last year and has a quarterback-like impact on the defense as far as production. When Polamalu is fully healthy and on the field, they are a versatile and unique team—without him they are just another good defense.
With Polamalu under contract, the Steelers will also have the franchise tag available for their next biggest priority in Mike Wallace next offseason. Wallace should also be signed to a long-term deal, but being able to prevent him from hitting restricted free agency is a bonus for the team's negotiating position.
He will likely get a big deal—larger than Eric Weddle's deal according to Jason LaConfora—but had he put up a second defensive-MVP-type of season, then his demands on his new deal could have been astronomical. While Polamalu himself is a very spiritual person who is obviously not motivated by money, these things can get muddled with agents and impending free agency is involved.
Needless to say, Kevin Colbert and Omar Khan know what they are doing as they are some of the smartest veterans in their respective roles for the team.
Troy Polamalu is happy to retire as a Pittsburgh Steeler, and every single Steelers fan will be happy about it too.