It could become painfully evident Sunday how little the Pittsburgh Steelers are getting from their younger players on defense.
Harrison, the 2008 NFL Defensive Player of the Year, is still recovering from a knee problem that has hampered him since spring. Polamalu, the 2010 NFL Defensive Player of the Year, hurt his calf in the Week 1 loss at Denver, although it's unclear when he was injured.
The Jets have their own injury problems on defense. Four-time Pro Bowl cornerback Darrelle Revis suffered a concussion in the opener and is out Sunday, as is linebacker Bryan Thomas, according to the New York Post.
The Steelers felt Harrison's absence in their 31-19 loss to the Broncos, and they're 6-7 in games Polamalu has missed since 2009. One of those losses came against the Jets at Heinz Field in 2010.
According to the Pittsburgh Tribune-Review, the Steelers have never been without both Harrison and Polamalu, who have been to a combined 11 Pro Bowls, in the same game.
That doesn't seem to bode well for the Steelers as they try to avoid their first 0-2 start since 2002.
The Steelers went to the Super Bowl in each of the years Harrison and Polamalu were named the league's top defensive player. But Harrison is 34, and Polamalu is 31. It's time for the Steelers' championship-caliber defense to pass the baton to younger players.
The problem is there's not much evidence to suggest the new crop of defenders is ready to take the baton, and that's forcing older players to carry too much of the load.
Which team's defense will be more affected by injuries, Jets or Steelers?
Ryan Clark, the Steelers' leading tackler last season, was missed in Denver both in last year's playoff loss and last week's season opener. He'll turn 33 next month.
The Steelers would be in similar trouble without Ike Taylor (32), Larry Foote (32) or Brett Keisel (34 on Wednesday).
The only Steelers defenders younger than 30 who've had that much of an impact are LaMarr Woodley and Lawrence Timmons. Both were drafted in 2007, the same year Harrison became a starter.
With the possible exception of nose tackle Steve McLendon, the heir apparent to 35-year-old Casey Hampton, the Steelers haven't added any significant contributors on defense since 2007. Most of us weren't even on Facebook then.
Ryan Mundy, drafted in 2008, obviously didn't do enough to fill Clark's shoes in Denver. What makes anyone think he can fill Polamalu's shoes Sunday? He's the top backup at a position where the Steelers have little depth.
Ziggy Hood, the Steelers' 2009 first-round draft pick, is by no means a bust, but he needs to take his game up a notch or two and become more of a game changer like Keisel has on the other side of the defensive line.
Keenan Lewis is another member of the Steelers' 2009 draft class who should be rounding into his prime but still isn't a finished product.
Lewis won the starting cornerback job opposite Ike Taylor, but he missed some tackles in the season opener and often doesn't seem to be in the right place in coverage.
Lewis beat out 2011 fourth-round pick Cortez Allen for the starting job. Allen also allowed yards after the catch with missed tackles in Week 1.
Cornerback Curtis Brown, drafted in the third round in 2011, is nothing more than a special teams player at this point.
The 2010 draft yielded linebackers Jason Worilds and Stevenson Sylvester, who is out with an injury.
Worilds, a second-rounder, had a sack in Denver but like the rest of the Steelers' defense was helpless when Peyton Manning went no-huddle. He seems to be further along as a pass rusher than 2011 fifth-round pick Chris Carter and should start Sunday in place of Harrison.
The aging Steelers defense likely will get no infusion of youth from the 2012 draft class. Sean Spence is out for the season, Alameda Ta'amu isn't good enough to be activated and Terrence Frederick was cut.
Time will tell how much the 2011 draft class, which also includes first-round defensive end Cameron Heyward, will benefit from its first full offseason of workouts with the team.
Maybe it's too much to ask for the next wave of Steelers defenders to match the Steelers' current defensive core, which has taken the franchise to three Super Bowls since 2005.
Not many teams go to three Super Bowls in six years, and not many teams have a defense like the 2008 Steelers. They allowed fewer yards per game and per play than the storied 1985 Chicago Bears defense, according to the Chicago Tribune.
Perhaps this is a once-in-a-generation defensive unit that's fading away. Perhaps it will take years before a comparable defense can be built in the Steel City.
If what we see is what we get from players like Worilds, Hood and Lewis, the Steelers' problems on defense will go far beyond not having Harrison and Polamalu against the Jets. Steelers fans will learn just how spoiled they've been.
But if those Steelers defenders who don't own Super Bowl rings want to eventually win one, they'll need to have breakout seasons, and the time for that to happen is now.