PITTSBURGH — Cam Heyward can do the math. Then again, it's not that hard. The longest-tenured defensive player in Pittsburgh Steelers history knows he has far more football behind him than he does in front of him. How much more is anybody's guess, though if you watch him on any given snap — when the seven-time Pro Bowl defensive tackle's motor appears to run just as hot at 36 as it did at 21 — it might be longer than you think. Still, Heyward learned long ago that opportunities like the one that arrives Monday night, when the AFC North champion Steelers (10-7) host the Houston Texans (12-5) in the opening round of the playoffs, don't come around that often. The 15-year...
