James Harrison can still help Steelers but don't expect starter's snaps at 37

This is the second in a three-part series examining three key Pittsburgh Steelers who have at least 10 years of NFL experience (excluding Ben Roethlisberger). The Steelers have injected youth into the roster but still need these three aging veterans to produce.

Name: James Harrison

Position: Outside linebacker

Age: 37

Experience: 11 full NFL seasons (10 with Steelers)

Why the Steelers still need him: Check out Harrison's Instagram and tell me this dude isn't getting himself ready to play. He's running sprints in nearly 200-degree heat indexes while wearing 12-pound weight vests underneath a heavy hoodie? Harrison played well enough last year -- with 5.5 sacks and 14 pressures in 472 snaps -- to earn a two-year extension at age 37. There's enough uncertainty with Pittsburgh's outside linebackers to deem Harrison necessary. If the Steelers label him a situational, 25-downs-a-game rusher, well, Harrison says he could handle 25 snaps when he's 50. He still wants to start but can adapt to any role. You can pair him with Arthur Moats on one side, or start him until first-rounders Jarvis Jones or Bud Dupree are ready. He can still handle run-game duties. Your team is not in trouble if Harrison is your starter in Week 1.

Why the Steelers can question how much he has left: Your team is in trouble if Harrison is your starter in Week 1. No, wait -- you just said you aren't in trouble if that's the case. Well, it's complicated, because though Harrison can still produce respectably, it's probably not a good sign if two first-round picks can't beat out a 37-year-old that's been cut twice in as many calendar years. The Steelers are heavily invested in Dupree and Jones and needs to see them succeed. New coordinator Keith Butler could ask outside linebackers to drop into coverage more often than Dick LeBeau did, which probably doesn't favor Harrison. Harrison can get by with strength and pass-rush savvy but the Steelers aren't expecting the 2008 explosion. They aren't paying him for that (two years, $2.75 million). It's fairly clear Pittsburgh needs Harrison to bridge the gap with another 400-to-500-snap performance. Last year's production was a resurgence of sorts, with Harrison eschewing retirement to sign with Pittsburgh. Any flashes of the once-dominant force will be welcomed but not expected.

Final word: Make no mistake, Harrison's presence will help this defense. If Jones struggles with injuries again or Dupree's not ready, Harrison could play major snaps in 2015. But the Steelers won't be at their best if he's forced to play entire games.