By the numbers, the Steelers had the top defense in the NFL last season, allowing the fewest yards. In points allowed, they were second best.

Numbers can lie.

The bulk of those sterling statistics was achieved in the first three quarters of the season when the Steelers were 9-3 and looked like a Super Bowl contender. Over their final five games, including one in the playoffs, they were 1-4 and allowed 145 points as their vaunted defense collapsed. They had the look of not just another team, but another bad team.

Some of that decline -- but not all -- was the result of an injury Dec. 9 to defensive end Aaron Smith that kept him out for the remainder of the season. Smith is healthy this season, another aging veteran on a unit that will be supremely challenged.

Not only do the Steelers have the most difficult schedule in the NFL, but their opponents also are particularly strong on offense. The Steelers will be facing seven of the top 10 offenses in terms of yards from last season and six of the top eight in points scored. Considering how they finished and considering what was a veteran defense is now a year older, there have to be grave doubts about the unit's ability to handle the challenge it faces.

It becomes especially daunting late in the season when, in successive weeks beginning Nov. 9, the Steelers face offenses that were ranked third (Indianapolis), fifth (San Diego), 11th (Cincinnati), first (New England) and second (Dallas) in scoring in 2007.

Can this older unit hold up against such pressure?

Three of the starters have double-digit years of experience: Inside linebacker James Farrior is in his 12th season; cornerback Deshea Townsend his 11th; Smith his 10th. Nose tackle Casey Hampton has eight years of experience, end Brett Keisel, inside linebacker Larry Foote and safety Ryan Clark seven, cornerback Ike Taylor and safety Troy Polamalu six and outside linebacker James Harrison five. Only second-year outside linebacker LaMarr Woodley is a kid.

The fact that the Steelers have what looks to be a potent offense can take some of the pressure off the defense. They have one of the premier quarterbacks in the league in Ben Roethlisberger and a very good running back in Willie Parker. Hines Ward remains a top possession receiver, and Santonio Holmes could be ready to step up into the ranks of the elite deep threats. He led the NFL in yards per catch last season. Tight end Heath Miller is another high-caliber offensive player.

The Steelers might need all of that offense as they take on their difficult schedule, which also includes such playoff contenders as the Super Bowl champion New York Giants; the Jacksonville Jaguars, who beat the Steelers twice last season; the Philadelphia Eagles, the No. 6 offense in the league last season; and the improved Washington Redskins.

The difficulty of the schedule is a bit overrated because the Steelers' chief competitor in the AFC North, the Cleveland Browns, plays a similar schedule, although with one notable exception: The Browns don't play the Patriots. The Browns play Dallas, the Giants, Washington, Jacksonville, Indianapolis and Philadelphia.

The bottom line on any season is not statistical rank but rather wins and losses. The Steelers' defense will perform adequately and the offense exceptionally. If it were not for such a difficult schedule, the Steelers would win 11 or 12 games. With this schedule, they should win nine, and that will be good enough to win the division. It's possible eight wins might earn a title in the AFC North.

Here are the teams the Steelers can beat: They'll win five games among their division opponents and add victories against Houston, the Giants, Washington and Tennessee. That will put them in the playoffs where they'll lose in the first round.

In free agency and the draft, they'll be looking for defensive players.

This once-excellent defense is fading fast. It might have one season left in it, but no more.