The Steelers have had to deal with problems on the offensive line and even injuries to quarterback Ben Roethlisberger in the past. The most disturbing part of Pittsburgh's 2-2 start is the struggles with its historically tough run defense.
Houston's Arian Foster, the reigning, albeit banged-up, NFL rushing champion, ran for 155 yards against the Steelers. After allowing just one 100-yard rusher in their previous 50 games before the 2011 season, the Steelers have now allowed two in four weeks (the Ravens' Ray Rice was the other).
The Steelers' defensive front is getting pushed back, and Troy Polamalu along with the linebackers are missing tackles.
Last season, Pittsburgh led the NFL in run defense, giving up 62.8 yards on the ground. Through four games this year, the Steelers have almost permitted double that, allowing 119.5 yards rushing per game (which ranks 23rd in the league).
Next up for the Steelers' defense is Titans running back Chris Johnson, who seems to be getting back on track.
STAT THAT STICKS: Minus-10. That's the awful turnover differential for the Steelers, which ranks worst in the NFL. Pittsburgh has forced one turnover while giving the ball up 11 times. No one is even close to the Steelers. The second-worst differential is minus-6 (Philadelphia and Denver).
OVERHEARD: "I guess if there's a time to not be quite right, it's early in the season. We've been down this road enough times that we know it's about when you get hot. If we can pull together offense, defense, special teams and get hot at the right time, that's all that matters." Roethlisberger after the Steelers fell to 2-2 for the second time in three seasons.
LOOKING AHEAD: The Steelers (2-2) play host to the surprising Titans (3-1), who ended a seven-game road losing streak with a win at Cleveland on Sunday.