Season preview positional analysis: DL

SFI will break down the 49ers by position leading up to Sunday's season opener against the Arizona Cardinals, with keys to the season for each unit, player to watch, strengths and weaknesses, key stats and facts, key arrivals and departures and the bottom line regarding whether the team is better or worse at the position compared to last season. Today: Defensive line

In their annual quest to improve along the defensive line, the 49ers had work to do this year after losing Bryant Young to retirement and Marques Douglas to free agency.

Those two bookends of the team's 3-4 front were two of San Francisco's best defensive players in 2007 and ranked among the team leaders in both tackles and sacks.

The defensive front will have a new look without the two veteran stalwarts, but during the summer it looked pretty good. Newcomer Justin Smith and second-year player Ray McDonald showed promise manning the right side, and Isaac Sopoaga - retained by the team with a lucrative contract extension - looked like a natural at left end.

As the team attempts to stick to a true 3-4 base system, the pieces appear to be in place for success - but expect to also see a lot of shifting into a 4-3 set during the season and during the course of games as the 49ers attempt to get the best use out of their personnel and continually keep opponents off-balance.


KEYS TO THE SEASON

Protecting Patrick:
After his spectacular rookie season of 2007, the 49ers are now building their defense around middle linebacker Patrick Willis, and it's the job of the guys up front to keep bodies off the NFL's reigning leading tackler. The 49ers want the guys up front in their 3-4 scheme to absorb linemen and blockers so that Willis will be free to roam and make plays.

Push in the pass rush: The 3-4 scheme is designed for the outside linebackers to provide most of the pressure and make most of the sacks on passing downs, but that doesn't mean the guys up front don't need to be factors when opponents go back to pass. Young led the team with 6.5 sacks last year and Douglas was fourth with three, so the new guys in their place need to pick up the slack in their absence.

Hold the point of attack: The front wall needs to stay assignment true to fill gaps and clog the running lanes so that the defense can be successful stopping the run. In other words, the 49ers can't get pushed around up front, which has occasionally been the case in recent seasons.

The bottom line: Despite the loss of Young and Douglas, the 49ers actually appear improved in this area, which is something of a surprise considering it didn't look that way entering the summer. McDonald and Sopoaga have shown a lot of promise as the new starting ends, and they'll be helped out by the team's use of newcomer Smith as a hybrid end/outside linebacker.


PLAYER TO WATCH/Isaac Sopoaga

The light finally went on for Isaac Sopoaga last season, when he finally was able to synchronize his brain with his brawn to become a factor up front for the 49ers after developing slowly since the team drafted him in 2004. But now that Sopoaga understands his assignments and role in the system, he can be a playmaking beast. One of the NFL's strongest players, Sopoaga became a key contributor in the team's defensive line rotation in 2007, and it convinced the 49ers not to let him hit the open market in March as a free agent. Instead, the 49ers lavished him with a five-year, $20 million contract extension and plunked him down at left end, where Sopaoga looked comfortable this summer after spending most of his time at nose tackle earlier in his career. Sopoaga easily held off first-round draft pick Kentwan Balmer with his play on the edge, and how he performs there this year will be consequential in the team's defensive success.


UNIT AT A GLANCE

Starters for season opener:
LE Isaac Sopoaga, NT Aubrayo Franklin, RE Ray McDonald, HYBRID Justin Smith
Reserves: DT/E Ronnie Fields, E Kentwan Balmer
Key new arrivals: Justin Smith, Kentwan Balmer
Key departures: Bryant Young, Marques Douglas
Defensive line coach: Jim Tomsula, second year with 49ers, second year of NFL experience

Strengths: Good size and strength up front in end Isaac Sopoaga and nose tackle Aubrayo Franklin. A young up-and-comer at right end in Ray McDonald and a play-making force on the right edge in Justin Smith, who will be moved around throughout the defense. Solid backups in Ronnie Fields and rookie Kentwan Balmer, who both will see regular roles in the line rotation.

Weaknesses: Sopoaga still is unproven at end, and Franklin has not proven he can be a force in the middle. This unit has a lot of production to make up for in the pass rush after the offseason loss of 2007 starting ends Bryant Young and Marques Douglas.

Fact check: Although opponents rushed the football 504 times against the 49ers in 2007 - the third-highest total in the NFL - they averaged just 3.8 yards per carry, which was the fifth-lowest average allowed in the league. Since coach Mike Nolan's arrival in 2005, the 49ers have allowed opponents an average of 3.87 yards per rushing attempt, which ranks seventh in the NFL over that span.

Vital stat I: 30: Quarterback sacks recorded by the 49ers in 2007.

Vital stat II: 13: Quarterback sacks recorded by San Francisco defensive linemen in 2007.



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