While I understand those concerns, the backbone of the team has clearly been the defense and I see a few issues that could prevent the Steelers from contending for another title in 2009.
The defensive line is the first question mark due to the average age and questionable durability of the starters. Casey Hamption, Brett Keisel, and Aaron Smith are all over the age of 30, with Smith being the oldest at 33.
The reserves on the current roster are also over 30 except for Nick Eason (28) and first round pick Evander Hood. The Steelers rely heavily on the front three to create significant penetration to allow the dynamic linebackers and blitzing secondary to make the big plays.
Last year, Hampton missed three games and Keisel missed six, while Smith missed a portion of 2007 with a torn bicep. The Steelers cannot afford to lose any of the three starters because replacing 123 tackles and 7 1/2 sacks is extremely hard.
The linebackers are the strength of not just the defense, but the team. James Harrison and Lamar Woodley combined for 27 1/2 sacks last year and even though the Steelers released a very productive Larry Foote recently, it would not surprise me to see Lawrence Timmons emerge this year like Woodley did last year.
Many people forget that Timmons is only 23 and has the athleticism to be a major factor in the schemes of Dick LeBeau. Again, depth could be a concern for the Steelers. However, if the last decade or so has proven anything, the Steelers system continually produces star after star at linebacker.
One player to watch is second year player Donovan Wood from Oklahoma State. After a promising beginning last year, Donovan continually struggled with hamstring injuries that prevented him from contributing. At 6'2 230 pounds, Donovan could develop into a solid inside linebacker with some experience.
The secondary features All-Pro strong safety Troy Polamalu, hard hitting Ryan Clark, Ike Taylor, and aging veteran DeShea Townsend. The Steelers lost Bryan McFadden to Arizona via free agency, but the Steelers drafted two promising prospects in Keenan Lewis and Joe Burnett to compete for the open nickel position this year.
Although the yards per game given up via the pass last year was No. 1 at just over 237 yards per game, this group is the beneficiary of the play from the front seven—especially the pressure supplied by Harrison and Woodley.
Taylor is still inconsistent and Townsend has lost more than half a step since he entered the league 12 years ago. This group manages to receive favorable reviews mainly due to the play of Polamalu, but that shouldn't be the case. This is the second weakest group of players behind the offensive line and one injury to Polamalu could spell disaster.
Last year was obviously a special year for the Steelers defense: No. 1 against the pass, No. 2 against the run, and No. 1 in total yards per game to go along with 51 sacks. The linebackers speed and athleticism allow the Steelers to protect a very average secondary in pass coverage and assist a strong but aging front three against the run.
Injuries are part of the game but the wrong injury to this defense could cause a dramatic drop not just in stats but wins. The players seem to love Mike Tomlin and he seems to get the most out them week in and week out, but will the continual effort over the course of the year cause this roster to tire and suffer? I guess we're going to find out.