IDP rankings for Week 4

As the inescapable attrition of the season mounts, rosters -- both real and imagined -- erode, and depth becomes a key characteristic of contention. Just this past weekend we saw Cameron Wake, arguably the most consistent pass-rusher of the past several seasons, injured with what bodes to be a multiweek stint on the sideline. The bug bit Atlanta's Sean Weatherspoon already, and San Francisco may be without stalwart Patrick Willis this week. These are all major fantasy investments and there are no real handcuffs on this side of the ball, so it's next man up, mostly likely from a different NFL roster, when one of our defensive studs is ailing.

The good news is that defensive production can be far more plentiful than the expectedly picked-clean offensive wire can be at this point of the season. Given how many strong commodities continue to float for free in IDP leagues all over, we can look to some of the names and numbers below to help in replacing any lost talent, or to simply bolster defensive rosters as the campaign marches on.

Front Four: The weekly word on the world of defenders

Tracking trends: In the pursuit of production, especially the free kind, it often helps to check in on some of the developing statistical stories on the defensive side of the ball. With digging deeper in mind, we'll use this entire section to look into some telling trends we're noticing through the first three weeks.

Solo artists: In most IDP formats, greater value is given to solo tackles versus assisted tackles, as it's often a 2-1 ratio in terms of the fantasy point value. The top-10 list of solo artists so far has some expected names such as Jerod Mayo, Mark Barron and NaVorro Bowman, but you'll also notice that rising commodities such as Tyrann Mathieu -- aka the "Honey Badger" -- and fellow rookie Alec Ogletree rank quite high here. Both are available in the majority of ESPN leagues and have sustainable value given their steady tackle per snap rates.

Robert McClain is the "who is that?" award winner so far in the solo department, but it's simply a case of a corner getting highly targeted and keeping busy corralling offenders in his path. I wouldn't place a ton of stock into McClain outside of deeper leagues that roster corners.

Arizona's Karlos Dansby has enjoyed a renaissance campaign so far, with all of his tackles so far this season coming in the solo variety. When Daryl Washington gets back, the work won't be as easy to come by, but Dansby will still remain a fixture on the inside of that front seven. The greatest takeaway from this simple list might just be that all of these players are widely available in ESPN leagues and really outside of only McClain, each has enduring merit as a starting-caliber fantasy option.

Most Solo Tackles, This Season

Busy 'backers: No defender has been on the field more than Buffalo Bills linebacker Kiko Alonso this season. The rookie's 235 defensive snaps lead the league and it has led to some stellar statistical returns already (two picks, a forced and recovered fumble and on pace for more than 140 tackles). Owned in just 16 percent of leagues, it's getting sort of silly just how slow the market is moving on this kid's rare combo of stable floor and high upside. … Alonso's teammate, defensive back Aaron Williams, has been on the gridiron for just one snap fewer than Alonso and is quietly on pace for triple-digit tackles (available in nearly 90 percent of ESPN leagues). …. The Eagles' duo of DeMeco Ryans and Mychal Kendricks has been chasing down ball carriers all season and will be afforded another massive allotment of snaps in Denver on Sunday afternoon.

Rushing Houston: We've already coined Tamba Hali, Justin Houston and Dontari Poe as "H2-Poe," and are merely awaiting our first royalty checks. But until the revenue comes flying in, let's try to reap the rewards of just how special this pass rush group in Kansas City could be for fantasy purposes, particularly with Houston and his league-leading 7.5 sacks so far after destroying the Eagles and rookie Lane Johnson in Week 3 for 4.5 sacks on Michael Vick. Per Pro Football Focus, Houston rushed the passer on more than 90 percent of his snaps in Week 3, and was deployed at that rate in just two games in 2012. With increased opportunity to get to the pocket (overall pass rush rate is up to 70.3 percent after a 66.7 percent rate in 2012), Houston is delivering and starting to make us wonder if he can become as feared of a pass-rusher as the big guy playing for Houston. Considering that he's available in over 60 percent of ESPN leagues, there's great reward, and very little risk, in investing in Houston as he thrives on the outside for the Chiefs.

Bargain bin -- Defenders available in more than half of ESPN leagues

Green Bay's Brad Jones is an ideal stash if you can afford the dead roster spot this weekend while he's on bye, or add him next week if at all possible for his rare blend of sack upside and steady tackle production on the inside of the Packers' front seven. … We've championed him before, but Daryl Washington returns in Week 5 and there's little question whether he can step right in and resume an elite production pace. … Erin Henderson has always been a somewhat unexciting fantasy commodity, but that doesn't mean he's not a valuable resource for tackle production while playing on a defense that can't get off the field (he ranks 17th in NFL with 212 defensive snaps). … Robert Mathis is quietly posting another awesome season for Indianapolis, and has very real value in a league with strong rewards for sack production. … Baltimore's Daryl Smith is a top-10 fantasy linebacker so far, no matter how you slice it, and yet the inside 'backer for the Ravens is still available for free in the vast majority of leagues. … What is the major holdup in going after Chicago's Major Wright? He's playing center field for a team that gives up lots of hits (aka deep vertical targets). … Pittsburgh's Ryan Clark continues to be a steady enforcer and source for tackles even into the later stages of his career. … For those chasing sacks, Lions rook Ezekiel Ansah has been flashing on film for weeks now and the sacks are starting to show.

Week 4: The Top 25 linebackers, linemen and defensive backs

So that we're working from agreed parameters, we'll use what many consider traditional scoring modifiers for an IDP league: Tackle Solo (0.5), Tackle Assist (0.25), Sack (3), Interception (3), Forced fumble (3), Fumble recovery (3), Touchdown (6), Safety (4), Pass defended (0.5), Blocked kick (3).

Top 25 Linebackers

Top 25 Defensive Linemen

Top 25 Defensive Backs