In the parlance of the game, there are one-gap tackles and two-gap tackles, the former term typically used to describe interior defenders charged with getting upfield and creating penetration, the latter applying to linemen responsible for the holes on both sides of the blocker in front of them.
But in recent years, it seems that NFL talent evaluators have discerned almost no gap at tackle, at least when compared to defensive ends and in terms of overall importance to a front-four unit. Once seen as a grunt-level position, the tackle spot has emerged as a big-time growth area, as scouts have given it far more attention.
Certainly such an enhanced regard for defensive tackles has been reflected in the last several drafts.
"It looks, especially over the last few years, like the tackle position has finally caught up [to the defensive end spot] in how important it is to most teams," said John McCargo of North Carolina State, one of the top defensive tackle prospects in this year's draft. "Hey, it's about time, right? But, seriously, yeah, I think that the tackle position really has taken on more prominence. And I think we're seeing that in the way teams are drafting. I just hope it stays that way for one more year."
Actually, the tackle class of '06 might not be quite as talented at the top as other classes have been in recent drafts, but it still figures to produce at least two first-rounders (Haloti Ngata and Brodrick Bunkley) and possibly more. The crop of defensive ends, after coveted prospect Mario Williams -- a former teammate of McCargo's at North Carolina State and arguably the premier defender in the draft -- is relatively spotty.
So there is a chance that the trend of the past five years, during which tackles have outnumbered ends in the first round (21-18), could continue.
Not all that long ago, even the suggestion that tackles might supersede ends on the defensive-line pecking order would have been perceived as anathema. From a numbers standpoint, though, the two positions were relatively even in terms of first-day picks. In the 10-year stretch of 1986 through '95, 77 defensive tackles and 76 ends were chosen in the first three rounds of the draft. The glaring disparity was in the first round, where ends had a 37-21 advantage. Just once in that period, in the 1991 draft, did first-round tackles outnumber first-round ends.
During 1996-2005, there were 90 first-day ends and 87 first-day tackles. But in the last five drafts, the two positions have produced the same number of choices in the first three rounds (45). And in those five drafts, there were more first-round ends only once, in 2003.
Of particular note was the 2001 draft, which included a modern-era record six first-round tackles. That first-round bounty included standout interior defenders such as Richard Seymour, Marcus Stroud, Casey Hampton, Gerard Warren and the now-emerging Ryan Pickett. The second round in that '01 draft also brought the league Shaun Rogers and Kris Jenkins. It might be a while before any draft produces such a defensive tackle windfall.
"Up until around then," said Rogers, "I think teams just saw tackles as, you know, slugs. Just big guys who could take up space inside, [occupy] blockers and stuff things up in a very small, compacted area. But the drafts of the last few years have brought more athletic tackles to the league, more complete players, and it's a position that has earned a lot more respect."
That isn't to say teams don't still crave big-time defensive ends. Every club covets the great edge defender, the Dwight Freeney-type player who can explode off the corner, close on the quarterback and wreak all manner of havoc with a sack and perhaps a strip fumble. Those players turn games around, for sure, and they will always be premium prospects.
"Up until around then, I think teams just saw tackles as, you know, slugs. Just big guys who could take up space inside, [occupy] blockers and stuff things up in a very small, compacted area. But the drafts of the last few years have brought more athletic tackles to the league, more complete players, and it's a position that has earned a lot more respect."
Shaun Rogers, Lions DT
But with more teams using 3-4 fronts now, and with college programs churning out more hybrid defenders, the line between end and linebacker has been blurred a bit. Even if one considers the delineation between one- and two-gap defenders, there is no such murkiness at tackle. Not many of the tackle prospects this year, or in any recent draft, for that matter, were projected as potential ends. One exception was in 2005, when the Chargers chose Northwestern tackle Luis Castillo to play end in their 3-4 alignment.
Then again, almost without exception, it's tough to play defense these days without a dominant interior force. Consider the Super Bowl championship teams of the last six seasons: The Steelers' ability to stuff the run is keyed by the fireplug-like Hampton. New England has Seymour, arguably the most versatile front-four defender in the league. The Tampa Bay defense of 2002 featured Warren Sapp. In 2000, the Baltimore Ravens captured the Vince Lombardi trophy, in part, because the mammoth tandem of Sam Adams and Tony Siragusa jammed up everything inside and allowed Ray Lewis to run to the football.
"More and more, teams are building defenses from the inside out, and that's a little different take than we've had in the past," Kansas City Chiefs coach Herm Edwards said recently. "Obviously, you can't do that if you don't have tackles who can really play. You're never going to overlook the great pass rusher, right? But if there's a tackle out there, and that position has been really upgraded athletically now, it's hard to ignore the guy. You can control a lot of stuff if you've got tackles beating up [opponents] on the inside. And there are some really good tackles coming into the league lately."
Indeed, the overall upgrade at tackle around the league means teams don't have to reach as much to find players at the position. Because of the difficulty in locating viable tackle candidates, out of desperation franchises historically have rolled the dice and drafted players perhaps a round earlier than they should have. The success rate in identifying and selecting solid tackles is far better now than it was just a decade ago.
And that's because the tackles are better now.
Len Pasquarelli is a senior NFL writer for ESPN.com. To check out Len's chat archive, click here.