San Diego relying on Tucker to stabilize defense without Merriman

Shawne Merriman is out for the season and the San Diego Chargers will surely miss the infectious energy and intensity he brought on every snap, but the bigger problem for defensive coordinator Ted Cottrell is how to replace the complete skill set Merriman brought to the table, especially the pressure he was able to put on opposing quarterbacks off the edge.

In watching the film from the Chargers' Week 1 loss to Carolina, it is apparent Merriman's knee was hampering him. He was still dropping into coverage in base formations but was clearly not the same explosive player he was a year ago, and the decision to finally have surgery was the smartest in the long term.

In the short term, backup Jyles Tucker will step in for Merriman, and although Tucker is not quite at Merriman's level, he is strong and well-built for San Diego's base 3-4 alignments, has an explosive first step and pure speed and showed great hustle in limited duty last season. He will line up opposite OLB Shaun Phillips in base, and in sub-package four-man fronts we likely will see Tucker and Phillips bracketing Luis Castillo and Jacques Cesaire on the inside.

Cottrell used Tucker against Carolina in basically the same role Merriman would play, but until Tucker proves himself, Phillips will see more attention than usual from opposing offenses.

Both Merriman and Phillips could play either end spot in the Chargers' four-man fronts in their nickel and dime sub packages, and Cottrell also could stack them at the inside linebacker positions in sub, but opposing offenses likely will identify Phillips pre-snap and set the protection to his side. That means extra attention in the form of help from a tight end or running back, and Cottrell will have to find a way to counter that.

Cottrell could give an initial pre-snap look with Phillips and Tucker, then move Phillips around just before the snap. The hope would be to create confusion along the offensive line that would make it easier to overload one side or open up room for a zone-fire that would bring a cornerback out of the slot.

Cottrell is a fairly conservative coordinator who does not like to take many chances to get pressure, so with Merriman out, he's likely to use more four-man fronts and overloads that send multiple defenders through the same area. With three cornerbacks -- Antonio Cromartie, Quentin Jammer and Antoine Cason -- who can match up well in man coverage, there will be only minor tinkering on the back end, but expect some shuffling and a variety of looks up front until Cottrell is comfortable with what Tucker can do and how best to align his players.

And though Merriman is obviously one of the premier pass-rushers in the league, he also will be missed as a run defender when the Chargers are in their base defense. The outside linebackers in a 3-4 defense must be able to set the edge against the run and force things back toward the inside linebackers who are coming downhill. That requires excellent technique in terms of hand use and finding leverage points against blockers -- things Merriman is very good at -- and it will take some time for Tucker to learn the finer points of playing the run. This becomes even more of an issue when taking into consideration the suspension that is costing ILB Stephen Cooper the first four games of the season.

On the other side of the ball, the San Diego offense will have to play more of a ball-possession style. Look for more emphasis on controlling the clock and moving the chains with RB LaDainian Tomlinson and TE Antonio Gates, and expect QB Philip Rivers to be more careful with the ball to avoid putting undue pressure on a defense that is somewhat in flux.

In the end, a big part of how the defense responds will depend on how well Tucker performs in the first full-time duty of his career. If he can step in and consistently play the same role as Merriman, the coaching staff won't have to upset the apple cart and players won't be asked to move around and do things they aren't used to.

Tucker has shown the kind of impressive physical gifts that could make him an impact player, but he must quickly improve his recognition of blocking patterns against the run and route recognition against the pass if he hopes to minimize the impact of Merriman's absence.

Scouts Inc. watches games, breaks down film and studies football from all angles for ESPN.com.