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Probably the most underrated positional unit the Pittsburgh Steelers have had in their run of success over the last decade as been their defensive line.
DEs Aaron Smith and Brett Keisel flanked NT Casey Hampton and back-up NT Chris Hoke, and all of them contributed extensively to a run of run-stopping dominance in that time.
Smith and Hoke are retired, Hampton is probably on his last leg (pun intended), and while Keisel still plays at a high level, the jury is still out on DE Ziggy Hood. The spotlight will be on him this season, heading into the critical fourth year of his five-year rookie contract.
Cameron Heyward, the back-up at both defensive end spots, is more of a concern. With Keisel's age and contract next season, the Steelers drafted Heyward to eventually be groomed into a starter, but thus far in 2012, he hasn't showed he's capable of playing extensive snaps, let alone start.
I spoke with a well-placed source who said the Steelers are disappointed in Heyward's development to this point, and his propensity to fight. Heyward got in three altercations during training camp, two against rookie OL Kelvin Beachum and one against LG Willie Colon.
Heyward, through two preseason games, hasn't played with the starting group, and hasn't really flashed anything going against the 2s, either. Heyward is gifted athletically, and his strength and quickness are apparent, but he looks slow to react to the play after the snap. HIs athleticism doesn't help much if he isn't anticipating what the offense is doing.
While he is young, the Steelers' alleged disappointment in the second-year player is understandable. Keisel has been injured multiple times the last two seasons, and defensive line coach Johnny MItchell rotates the linemen as often as the depth of the team lets them.
By this account, it doesn't seem like depth within the defensive line is an advantage the Steelers currently enjoy
Another point of frustration the source noted was with rookie NT Alameda Ta'amu, of whom the source said "doesn't get it." That's not necessarily a bad thing, but Hampton is not only just returning from a torn ACL, he's hinting at having had elbow surgery as well. NT Steve McLendon has proved to be at worst a serviceable back-up to Hampton, but between a second-year defensive end who's frustrating coaches on his lack of progress and a rookie who, by the source's account, isn't ready to see the field, one injury could create a problem within a unit that once prided itself on being one of the best in the NFL.