There's been plenty of explanations for this unusual draft class. I am of the school that believes this could be a product of a better understanding of the new CBA that includes a strict rookie wage scale that has reduced the emphasis of 3-down value at positions, opening up high draft picks to scheme and specialist selections such as Irvin. The claim here is that the money paid to that pass rushing specialist as a first round pick is still a bargain in comparison to a free agent pass rusher of the same value. For example, at this point it would cost more to sign someone like Osi Umenyiora, than it would for the Seahawks to have Bruce Irvin on the roster. That rookies cost less than veterans is not a new revelation, but what the Seahawks have done with this notion is astounding.
Consider this: The starting Seahawks secondary (Thomas, Chancellor, Sherman, Browner), whom SI's Peter King claimed before the draft is the best secondary unit in the NFL, has a combined salary cap hit of $2,568,856 according to spotrac.com. That's three Pro Bowlers and one borderline Pro Bowler for around a quarter of what New York Jets cornerback Antonio Cromartie alone will make this season. The Seahawks know how to work the hard salary cap and recognize (as many others do, admittedly) that the best value resides in rookie contracts.
Further, the Seahawks are drafting players (or signing in Browner's case) with specific roles in mind for them. The scouts do a good job of letting the coaching staff know exactly what each player they bring in does well and does poorly on the field. Chancellor, Sherman, and Browner, the bargains in this secondary were all knocked down in value going in their respective drafts because they were only good at one or two things and lacked the all around skills to ever be prototypical, traditional safeties or corners. Well, the Seahawks don't use any of those players in traditional roles. For example, they use Chancellor in the box or in a mid-level zone where he can keep the play in front of him, but still be a short distance away so his lack of top-flight range isn't exposed. He's not good in coverage and the Seahawks don't often put him in coverage.
Similar things can be said for Browner and Sherman, who both thrive as press corners, but can struggle in other areas. Smartly, the Seahawks line them up in press coverage as much as they dare to without getting too predictable in their scheme. Even in off man coverage, the Seahawks trust both players' length and pursuit speed to make up for their slow turn around caused by their height. The coaches do their best to ask their players to do exactly what they are capable of and nothing more. That's what makes their draft strategy so interesting.
Where the Seahawks get a little advanced in comparison to other teams is their philosophy of high volume picks. The Seahawks traded down twice this year to accumulate a total of ten draft picks. Having that many picks affords them some flexibility in that 1) the higher number of picks, the higher number of good picks, 2) late round draft picks are easy to get off of the roster and cap if the players don't work out due their low salaries, and 3) the low salaries translate to tremendous value when the players do work out. Because the Seahawks emphasize volume (and their recent success with UDFAs), it's important to consider all of the new players coming in, not just the drafted ones.
Including the undrafted free agents who have signed with the Seahawks, the team will be bringing in twenty rookies this season (see the list of drafted and undrafted). Most of them will most likely not make the final roster, but that doesn't matter nearly as much to the Seahawks as getting to coach them and practice them and get a better feel for what the exact strengths and weaknesses are of each player. First round pick Bruce Irvin will get the highest salary of the twenty rookies, but don't expect the others (with the possible exception of LB Bobby Wagner and QB Russell Wilson) to make more than a million dollars against the cap this season.
The advantages of bringing in so many players with so many chances to find the exactly right player for the exactly right role on the team include the flexibility to draft on need instead of perceived value. It's the main reason fans shouldn't panic when the Mel Kiper's of the world blast this organization for not getting better value out of their picks (along with the obvious reasons that these guys are wrong all the time and draft grades are ridiculously premature). The Seahawks are able to make these picks because they aren't making "need" picks in isolation. They're doing it as a piece of a larger roster philosophy that incorporates role needs, on-field scheme, salary cap, and accurate scouting.
The selection of Bruce Irvin a round ahead of where most media experts had projected him was immediately met with rebuke because they didn't understand what the Seahawks are doing. It's not hard to do. The organization is running a different system than what people are used to seeing. Since Pete Carroll is the head of both the front office and the coaches, he is in a unique position to more fully incorporate those two branches of the team. That means the front office isn't drafting players with the coach's scheme in mind. The coach is drafting players with roles in mind for each one. Cue Bruce Irvin again.
With his combination of speed and raw pass rushing ability, Irvin is the ideal Leo defensive end, the same position that Chris Clemons currently plays. Irvin offers similar speed and burst to 2011 Defensive Rookie of the Year Von Miller and will play a position that practically manufactures sacks. Clemons has had back-to-back 11 sack seasons after only getting more than 4 sacks once in his five seasons prior to coming to Seattle. He is a pass rush specialist whose weakness against the run is compensated for with a combination of Red Bryant, Kam Chancellor, and linebacker scheming. The same accommodation will be given to Irvin. To me, his sack totals will be directly correlated to how many downs he plays. The more third downs, passing downs, and Clemons substitutions there are, the more Irvin sacks we'll see. Expect him to get more time on the field as the season goes on, much like pass rush specialist Aldon Smith did last year with the 49ers. Like Smith, Irvin has the potential to get double digit sacks this season if the rest of the defense is clicking around him (and it has a very good chance to).
That's what the Seahawks are looking for in each player they bring into camp: a role that they can thrive in. Some roles are harder to fill (Earl Thomas and Red Bryant are two hard-to-replace pieces due to their physical gifts) and some roles are easy to fill (the team didn't bat an eye when they let David Hawthorne and LeRoy Hill test the free agent market). The Bruce Irvin pick especially demonstrates that the Seahawks value physical talent and a high motivation over anything else. Throughout this draft the Hawks selected for speed and physicality. You can't teach speed, they say, and the Seahawks are firm believers in that adage. Look at the players who would be hard to replace on this defense: Thomas and Bryant. Both are specimens that are simply hard to replace on a physical level. I think this is the template for how the Seahawks are drafting.
The Bobby Wagner selection is an example of the Seahawks desire to have insurance in other places on the roster in case their main cog, Earl Thomas, goes down with injury. Wagner possesses the kind of range and pursuit that can free up Earl Thomas on the next level when he's on the field and allow the coaches to put more pass rush on the field when both are out there covering the majority of the field between them. Wagner's speed and competitive nature are the reasons why he is on this team. He's a physical specimen. He ran a faster 40 yard dash than his college teammate and fellow Seahawk draft pick running back Robert Turbin. Seattle is using their top draft picks on amazing athletes that aren't available later in the draft and using later picks on players that they can get the most out of when the amazing athletes are able to cover up their flaws. It's the secondary all over again. Wagner will essentially be the Earl Thomas of the front seven, allowing players like Bruce Irvin to do exactly what he is capable of doing.
Why I trust the Seahawks front office so much is because they have a system, execute it well, and have the coaching to back it up. Over two years, they've had so many hits and have flashed so much savvy and potential, that they've quickly won me over. They use the draft to get the players they need before other teams can claim them. They use rookie free agency to find role players who can contribute in significant ways, like Ricardo Lockette's two long touchdowns last season. They use veteran free agency to get players who can fill gaps until they can get cheaper, younger replacements (Atari Bigby last season, for example). More than anything, the coaching is fantastic (especially Tom Cable--he is the reason I wasn't concerned they didn't draft an offensive lineman early). If you're a Seahawks fan, you should be very excited about this