No NFL team has a more prolific pair of pass rushers than the Giants’ starting defensive ends, Osi Umenyiora and Michael Strahan. With 12.5 sacks, Umenyiora is tied for second in the league, while Strahan, with 11.5 sacks, is tied for fourth.

Every team would be thrilled to have a pair of defensive ends who can rush the passer like Strahan and Umenyiora. But what makes them particularly valuable in the defense that coordinator Tim Lewis runs for the Giants is that they are the team’s only pass-rushing threats.

Most teams supplement their pass rushing defensive ends with quick defensive tackles or blitzing linebackers, but for the Giants, if Strahan and Umenyiora don’t get to the quarterback, no one does. The starting defensive tackles, Fred Robbins and Kendrick Clancy, have combined for just 2.5 sacks all season, and of the seven linebackers on the Giants’ roster, only one, Antonio Pierce, has recorded a single sack in 2005. In fact, after Umenyiora and Strahan, strong safety Gibril Wilson is third on the team with three sacks.

As a team, the Giants have 37 sacks this year, good for eighth in the league. But total sacks don’t tell the whole story. The Giants have more sacks than most teams because they have had more opportunities to sack the quarterback: Opponents have thrown 513 passes against the Giants, the second-highest total in the NFL. When the quarterback drops back to pass, the Giants sack him 6.7% of the time, which makes them an almost perfectly average team: Across the league, quarterbacks are sacked 6.6% of the time they attempt to pass.

As every Giants fan knows, the team hasn’t always gotten its pass rush from its defensive ends. During the 1980s and 1990s, no team epitomized the use of blitzing linebackers better than Big Blue and Lawrence Taylor. And Taylor wasn’t from alone: Pat Swilling, Derrick Thomas, and Kevin Greene all led the league in sacks from the linebacker position. Even as recently as 2001, four linebackers were among the Top 10 players in the league in sacks.

But in the four seasons since then (just as the Giants have increasingly come to rely only on their defensive ends to rush the quarterback), linebackers have become less prevalent among elite pass rushers throughout the league. The highest any linebacker has ranked in the NFL in sacks in the last four years was Washington’s LaVar Arrington, ninth in the league with 11 sacks in 2002.

Why have linebackers stopped being pass rushers? In large part it’s because they’re now used much more in pass coverage than they were even a few years ago. Opposing quarterbacks have learned to take advantage of the void in the middle of the defense that blitzing linebackers leave by throwing short passes to the tight end or running back in the spot the linebacker vacated. That makes blitzing a high-risk, high-reward proposition, and coaches are increasingly deciding that the benefit of a sack isn’t worth the risk of a short pass being turned into a long gain.

Pittsburgh Steeler fans might find it surprising that the Giants, with Lewis as defensive coordinator, don’t use their linebackers to blitz. Before joining the Giants last year, Lewis spent nine years as a defensive assistant for the Steelers, a team that became known as “Blitzburgh” for its frequent use of blitzing linebackers, including Greg Lloyd, Levon Kirkland and Greene.

But like all good coaches, Lewis designs his game plans around his team’s talent, rather than trying to force his preferred philosophy on a team that isn’t suited for it.

When head coach Tom Coughlin hired Lewis, the Giants already had Strahan and Umenyiora. Strahan was generally recognized as the best defensive end in the league, and although Umenyiora was coming off a rookie campaign in which he had only one sack, NFL personnel men had already begun salivating over his raw talent.(The Giants’ trade for Eli Manning on the day of the 2004 draft almost failed to materialize because the San Diego Chargers, who had the rights to Manning, insisted that Umenyiora be included in any trade, while the Giants were vehement that they wouldn’t part with him.)

So when Lewis surveyed his defense and saw a great veteran at one end, and a youngster with a rare blend of power and speed at the other, he decided not to import his “Blitzburgh” philosophy. Instead, he knew that his ends would provide all the pass rush he needed and focused on using his linebackers to shut down opposing tight ends and running backs in pass coverage.

In the first year executing the Lewis defense, the Giants struggled. Strahan missed half the season with a torn pectoral muscle, severely limiting the pass rush. The Giants also surrendered touchdowns on 72% of red zone possessions, making them the worst defense in the league inside the 20-yard line, where the shortened field makes linebackers’ ability to defend against short passes extremely important.

But this year, with Strahan back to health and Umenyiora playing the kind of football the Giants expected of him, the defense has thrived. And because the pass rush frees linebackers to defend against short passes rather than pursue the quarterback, new middle linebacker Antonio Pierce has excelled, intercepting two passes and deflecting eight more before going down with an ankle injury on December 11 against Philadelphia.

The Giants’ marked defensive improvement has made Lewis a candidate to become a head coach. If he ends up elsewhere in 2006, though, he won’t necessarily bring the same style of defense with him. Instead, he might very well revert back to the blitz-heavy style he coached in Pittsburgh. Lewis knows that the players are more important than the coaches, and wherever he ends up, he won’t have a pair of ends as good as Strahan and Umenyiora.

Mr. Smith is a regular writer for FootballOutsiders.com.