Consistency ratings: Week 5

The Pittsburgh Steelers have let us down.

Fantasy's No. 1 defense this preseason -- it finished the 2010 season with the most fantasy points (179), was our top-ranked defense and was selected 62nd on average in ESPN live drafts (average draft position: 63.6) -- the Steelers are off to a miserable start defensively. Their 22 fantasy points rank 19th, and through four games -- a quarter of their season -- their usually stout run defense ranks 22nd.

More disturbingly, they haven't been especially consistent, something that has been a strength of theirs in the past.

Beginning this week, and by popular demand, we're adding team defense/special teams to the Consistency Ratings. Your first Pittsburgh Steelers "Consistency Ratings" fact: This defense has already put forth two "Stiff" performances -- those judged as a point total of two or worse -- in four games this season. To put that into perspective, it had only one such total in the Steelers' previous 18 contests.

Forgive the Steelers their one-point performance against the potent Houston Texans' offense if you wish, but couple it with that minus-3 opening-week stinker against the rival Baltimore Ravens and it's clear this defensive unit is underperforming. Remember, the Steelers' defense managed 11, 6, 10 and 8 fantasy points against the Ravens in their four previous meetings. That is traditionally not a poor matchup for this defense.

Whether it's advancing age (James Farrior is 36, Aaron Smith 35, Casey Hampton 34 and Brett Keisel and James Harrison 33), poor tackling or a challenging few matchups for what has been a slow-starting run defense (Ray Rice was the Week 1 foe and Arian Foster Week 4), the Steelers' D has been a frustration to its owners thus far. Not that you should be entirely shocked, of course.

This is the reason we annually caution you not to overpay for a defense on draft day. Defensive performance fluctuates wildly from season to season.

The Consistency Ratings for the position over the past 34 weeks provide more compelling, supporting evidence:

To put those Green Bay Packers and New York Jets ratings (56.3 percent) into perspective, six quarterbacks, 14 running backs, 12 wide receivers, three tight ends and, perhaps most surprisingly, two kickers have had at least that good a number in the past 34 weeks. Plus, consider this: The Packers and Jets were "Stiffs" at least four times in those 34 weeks, and the Jets are the only defense to have been a "Stud" in fantasy as many as eight times. Of those 37 players at the skill positions to have managed a 56.3 percent Consistency Rating or better, 14 were "Stiffs" three times or fewer, and 21 were "Studs" more than eight times.

In other words, the numbers bear out the theory that defensive performance fluctuates rapidly -- somewhat comparable to that of kickers -- and that you're probably better off picking and choosing your matchups at that position more often than at any of the skill positions. Yes, the downside of picking the wrong defense/special teams is steeper; a whopping 16 of the 32 defenses have been "Stiffs" 10 or more times the past 34 weeks. That's why we ranked the Steelers first, and it's why defenses such as the Jets, Packers, Ravens and Steelers, who occupy the top four spots in the rankings on the above chart, were so highly regarded on draft day. If any defense is truly "safe," the numbers say those four are.

But keep in mind that weekly downside. There's a very good chance that even owners of the Jets' D might be smart to make one-week plug-ins off the waiver wire when the matchups dictate … such as this week, when the Jets make their annual trip to Foxborough. Care to guess how the Jets' D has performed in its past two visits there? Not well: minus-3 (Week 13, 2010) and 2 (Week 11, 2009). This could be a good week to pluck their stadium-partner New York Giants, available in 69.5 percent of ESPN leagues, as a free-agent plug-in.

Returning to the Steelers for a moment, let's not heap a world of hate upon their defense just yet. Those Rice/Foster matchups were tricky, and the Steelers' D does have two "Start"-worthy fantasy performances in their four games so far this season; only 11 defense/special teams have at least that many. The Steelers rank second overall in terms of total yards allowed per game (277.0) and fifth in points allowed per game (18.0), meaning their demise might, at least so far, have been greatly exaggerated. It's difficult to imagine, after all, that the effects of age would take hold so rapidly after merely one offseason.

This might be your No. 1 buy-low defense. Besides that tough-as-nails New England Patriots matchup come Week 8, the Steelers' remaining schedule is populated with mostly weaker offenses, including three matchups against teams led by rookie quarterbacks. In fact, look at their schedule the final eight weeks: @CIN, bye week (Week 11), @KC, Cin, Cle, @SF, StL, @Cle.

Position benchmarks

As always, the following chart lists the benchmarks for each of the Consistency Ratings designations. Players are rated for their 2011 performances alone, as well as their performances in the past 34 regular-season weeks (from Week 5 of the 2009 season through Week 4 of 2011).

Players' 2011 numbers are initially ranked by their VBD. Players' numbers in the past 34 weeks are initially ranked by the percentage of their teams' scheduled games in which their weekly point total was classified a "Start." All statistics are sortable by category.

(Note: Due to the byes in Week 4 of 2009, certain players could have appeared in as many as 33 games, instead of just 32. The four bye-week teams from Week 4 of 2009 were: Arizona Cardinals, Atlanta Falcons, Carolina Panthers, Philadelphia Eagles.)

Quarterbacks: 2011

Quarterbacks: Past 34 weeks

Running backs: 2011

Running backs: Past 34 weeks

Wide receivers: 2011

Wide receivers: Past 34 weeks

Tight ends: 2011

Tight ends: Past 34 weeks

Kickers: 2011

Kickers: Past 34 weeks

Tristan H. Cockcroft is a fantasy football analyst for ESPN.com. You can e-mail him here, or follow him on Twitter @SultanofStat.