Can the San Francisco 49ers' Defense Still Succeed After Loss of Key Starters?

The San Francisco 49ers have been tapped to be one of the primary contenders for the Super Bowl again in 2014, however, their much vaunted defense appears set for a downturn.

Through the last three seasons, the Niners defense has consistently ranked in the top five, however, their position as one of the elite units in the NFL appears to be under threat following a tumultuous offseason.

That is because San Francisco has lost a number of key defensive players to injuries and suspensions, leaving major roles to potentially be filled by members of the roster with limited or no experience. Many expect the 49ers to suffer from absence of key starters on the defensive side of the ball.

However, the coaching staff in San Francisco will hope that the depth acquired through an intelligent draft strategy will enable them to effectively fill the voids left by some of their most important defensive players.

But do the replacements tasked with taking the place of the likes of NaVorro Bowman and Aldon Smith have what it takes to keep San Francisco's defense a top-five unit?

Here I analyze whether the defense can succeed in 2014 without some of its biggest contributors.

The Losses

Let's start with a quick breakdown of the defensive players that the Niners will be without in their Week 1 matchup with the Dallas Cowboys on Sunday.

Heading into the offseason the 49ers knew they would be minus inside linebacker Bowman, who sustained a torn ACL and MCL in the 2013 NFC Championship Game against the Seattle Seahawks.

Bowman has now been placed on the Physically Unable to Perform list and will miss at least the first six weeks of the regular season.

The loss of Bowman—a three-time first-team All-Pro—was bad enough going into the new campaign.

But the hole in the 49ers' excellent linebacker core was doubled eight days ago when the NFL suspended pass-rush specialist Smith for nine games for violating the league's personal conduct and substance abuse policies.

Smith's suspension leaves the 49ers without a player that led the NFL with 19.5 sacks in 2012 for the majority of the campaign. 

Up front San Francisco also has problems, with nose tackle Glenn Dorsey, who has been placed on injured reserve/designated for return list due to the torn biceps muscle he sustained in early August. He is expected to be on the sidelines until late in the season

In addition to the absence of Dorsey, the 49ers' defensive front could also be in line to lose another key member following Ray McDonald's arrest on domestic violence charges.

McDonald is set to play against Dallas in spite of his possible misconduct, although it remains to be seen whether the 49ers will deactivate him down the stretch as the legal process takes it course.

The replacements

The Niners appear to have their replacements for those notable absentees pretty much set.

Michael Wilhoite outplayed rookie Chris Borland in preseason and, according to Paul Gutierrez of ESPN.com, has been confirmed by defensive coordinator Vic Fangio as the player who will take Bowman's spot in the lineup.

Meanwhile, the question over who will get the most reps in place of Smith is one that still needs to be answered.

Dan Skuta and Corey Lemonier shared the workload in 2013 when Smith missed five games after his DUI, helping the Niners go 5-0 in Smith's absence.

Fifth-round pick Aaron Lynch has shown a capability to rush the passer at an NFL level in his first preseason. He will also be in the mix, with Fangio—per Matt Barrows of The Sacramento Bee—insisting that he expects the trio to be prepared to step into the breach.

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At this point, really, it's not that tough because everybody's getting a lot of reps. If it was in the middle of the season and it happened without much of a warning, it might be a little tougher. But that's the way it happened last year...Guys just have to be ready to play.

"

Up front, Ian Williams—the starting nose tackle in 2013 before suffering a season-ending ankle injury in Week 2—will slot in at Dorsey's position as the anchor of the defensive line, while Tony Jerod-Eddie, Demarcus Dobbs, Tank Carradine and Quinton Dial should all be in the running for snaps if McDonald misses any time.

Are they good enough?

So we've gone through the defensive stars who will be missing for the 49ers to start the 2014 season and their prospective replacements. But what needs to be examined more closely is whether those fill-ins possess the tools to ensure there is no drop off in performance at those positions.

Michael Wilhoite

It was perhaps somewhat surprising that the Niners did not bring in veteran help in the offseason to provide extra competition at inside linebacker following Bowman's horrific injury.

Instead San Francisco opted to stick with what it already had in Wilhoite, who deservedly beat Borland to win the starting job alongside Patrick Willis. Willis, per Matt Maiocco of CSN Bay Area, appears likely to stay in his "mike" linebacker role in the Niners' 3-4 setup, while Wilhoite will come in and play Bowman's "jack" role.

Marcio Jose Sanchez/Associated Press

The 49ers obviously have faith in Wilhoite, who started two games in place of Willis in 2013 and played well alongside Bowman in big wins over the St. Louis Rams and the Houston Texans. That is a very limited sample size from which to judge him, although Wilhoite was impressively productive in preseason, recording 17 tackles and one sack.

Wilhoite looks to have the ability to perform capably against the run, but one of the key reasons why Bowman is one of the NFL's best linebackers is his skill in pass coverage.

In the 2013 season Bowman ranked as the top 3-4 inside linebacker in the league, per Pro Football Focus (subscription required), and received a regular-season grade of 6.6 in coverage.

Bowman also recorded eight passes defensed and two interceptions, with one returned for a touchdown in the famous "Pick at the Stick" play that sealed a Niners victory over the Atlanta Falcons in San Francisco's last game at Candlestick Park.

Those numbers are in stark contrast to those of Wilhoite, who in the six games in which he saw extensive action on defense in 2013 earned a grade of 0.7 from PFF in pass coverage. He struggled in that aspect of his game in preseason, receiving similarly poor grades for his performances against the Baltimore Ravens and San Diego Chargers.

Stepping in for a player of Bowman's caliber promises to be an extremely difficult task for someone who only has two career starts to his name.

Yet Wilhoite has already shown that he can perform at the highest level, the challenge for him now is to do it consistently and improve his play in coverage.

Dan Skuta and Corey Lemonier

As was noted earlier, the Niners were able to excel when Aldon Smith was on the sidelines for five games in 2013.

But only one of the teams San Francisco beat during that five-game winning streak had a winning record.

And, while the 49ers will be glad to get Smith back before their two meetings with the Seahawks, the nine-game run in which they will be without Smith encompasses multiple encounters against presumed playoff contenders, in addition to divisional clashes with the Arizona Cardinals and St. Louis Rams.

Still that should not be a daunting slate for Skuta and Lemonier, who gained some experience last year competing in big NFL games. However, their remain plenty of question marks as to whether they can prove as effective in 2014 as they did last season.

The primary concern, somewhat obviously, centers around the duo's pass-rushing abilities.

Skuta was the No.16 ranked 3-4 outside linebacker in the league last season, per PFF, but did not register a sack at any point during the campaign.

Lemonier did not fare much better, recording just one sack, although PFF did rate him as the most efficient rookie edge-rusher in the league last years, as he racked up 24 total quarterback pressures.

Coordinator Fangio—per David Fucillio of SB Nation—believes Lemonier is on his way to becoming a three-down linebacker.

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He's vastly improved as a linebacker, he is. You can see a big difference from him in year 1 to year 2. Still has a lot of room for improvement there, and it just comes with playing time. It's just recognition and reaction. He can tell you everything perfectly, it's just reacting and getting it done quick enough.

"

With Smith out of action, the Niners may need that improvement to come sooner rather than later, particularly in terms of the pass rush, although that could come from the exciting rookie Lynch.

Lynch caught the eye in preseason, consistently pressuring opposing quarterbacks. He has the potential to be an explosive weapon off the bench should the Niners choose to use him as part of a rotation.

Still, for all the potential of Lemonier and Lynch, the fact remains that neither possess Smith's prowess as a pass-rusher. They along with Skuta will need to play above themselves in order to negate the impact of the Pro Bowler's prolonged exile.

Ian Williams

Heading into training camp it appeared that Dorsey and Williams were set for one of more interesting position battles of the preseason.

Dorsey's injury ended that expected competition and now the focus is on Williams to make the nose tackle position his own. Williams is thought of highly within the 49ers organization and evidently had the tools to beat out Dorsey to win the job last season prior to his injury.

As with Wilhoite, the sample size to judge Williams from is small given that his injury came early in his first season as a starter. But Williams has impressed during the preseason practices, with Harbaugh—per Fucillo—stating that the former Notre Dame man has looked better than anticipated.

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Better than I thought he would in terms of Ian. He's looked good right from the beginning, right from the first day he was out there. I think our strength staff, our trainers and doctors have done a great job. And Ian himself, has done a fabulous job. So, it looks good right now, the way he's practicing.

"

Behind Williams Jerod-Eddie, Dobbs and Dial can all play nose tackle and, while the 49ers will have preferred to have Dorsey available, the drop-off appears more likely to come from the back end of the 49ers front seven than the D-line.

Keys to nullifying the damage

It seems to be widely accepted that the 49ers defense will suffer from a decline this season as a result of the loss of some of their key starters.

But how could San Francisco prevent that projection from becoming a reality?

The Secondary

While the 49ers front seven has been heavily praised over the last few years, the secondary has widely considered to be the weak point of the defense.

The back end of the defense also lost key players in the offseason, with Tarell Brown, Carlos Rogers and Donte Whitner all leaving for pastures new. It has been a slow transformation for a secondary that now looks unrecognizable to the one that lined up in the Super Bowl XLVII.

Many may see that as a criticism but, while the majority of the Niners' defensive backs are short on experience, what they do possess is tremendous potential.

Tramaine Brock and Chris Culliver will be the starting corners in 2014.

Neither are household names, but each has the capability to develop into one of the better cornerbacks tandems in the league.

Pro Football Focus

Brock exploded onto the scene in 2013, as he grabbed five interceptions and finished the campaign with 13 passes defensed, ranking ninth in the league in coverage among all corners, according to PFF.

Culliver missed the previous campaign as he recovered from a serious knee injury, however, his imminent return to regular-season action should excite 49ers fans, given that he put up 14 defended passes and two interceptions in helping San Francisco reach the Super Bowl in 2012.

The selection of Jimmie Ward in the first round of this year's draft is likely to give the Niners more playmaking ability from the nickel spot, although Chris Cook—despite making two interceptions in the preseason—still has some way to go to prove that he can be the physical press coverage corner he was signed to be.

San Francisco lost some physicality in the secondary with strong safety Whitner's departure, yet his replacement Antoine Bethea possesses considerable experience and should complement second-year free safety Eric Reid, who made the Pro Bowl in his rookie year after snagging four picks.

In short, this is a young and exciting secondary that is significantly underrated by most observers. In Brock, the group possesses a player who has the attributes to develop into a fine cover corner. 

The success of this group will depend on whether the likes of Brock, Culliver and Reid can build upon or at least maintain their previous levels of performance.

If they are able to do so, then that may take much of the pressure off a diminished pass rush.

Defensive line rotation

Much has been made of McDonald's recent arrest but, even if he is eventually reprimanded by the Niners or the league, San Francisco has the benefit of plenty of depth up front.

It was a luxury the 49ers did not have in 2013. Now—with Carradine and Dial coming into the fray—they have the opportunity to spell the starters on a more regular basis.

Player	Sacks	Hits	Hurries
Cornellius Carradine	1	3	6
Quinton Dial	0	0	5
Tony Jerod-Eddie	0	0	2

Both Carradine and Dial made an impression in preseason, with the former showing signs of the explosiveness that convinced San Francisco to select him in the second round, while Dial used his considerable size and eye-catching strength to put up 15 tackles.

Regardless of whether McDonald receives some kind of suspension, the added resources on the defensive line should be a huge aid to the team, particularly to the 34-year-old Justin Smith.

In spite of the Niners' lack of defensive line depth in 2013, Smith was still able to total 6.5 sacks in the regular season. Taking some of the workload away from the Cincinnati Bengal is likely to allow the veteran to remain effective as he approaches the twilight of his career. Keeping Smith fresh can only be a good thing for the 49ers given his aptitude as a pass-rusher and as a player capable of soaking up double teams to create gaps for others to pursue the quarterback.

Furthermore the presence of Carradine should also boost the Niners' ability to chase down the opposing signal-caller. Carradine's talents in that area were showcased in this year's preseason, as he posted one sack and six quarterback hurries, per PFF.

Yes, the Niners' linebacker corps will be without some hugely influential pieces to start the season. However, if San Francisco's defensive line rotation proves to be as deep as it looks, the impact of those losses could be somewhat nullified.

Patrick Willis

It would be fair to say that Willis has been overshadowed by Bowman at inside linebacker in recent years.

While Willis has been consistently excellent and is still the heart and soul of the Niner defense, it is Bowman who made the bigger plays in 2013. But with Bowman now on the sidelines, there will be extra onus on Willis to perform, as San Francisco aims to silence the doubters who have expressed concern about the team's defense going into the new season.

It would be wrong to suggest that Willis needs to make a drastic improvement on his form from the 2013 season, which was good enough for him to end the campaign ranked as PFF's No. 3 inside 'backer.

Yet with zero interceptions and just three sacks to his name last year, the big plays were lacking from Willis.

The seven-time Pro Bowler will undoubtedly lead by example, by his performance on the field. Bowman may well have impressed on a more regular basis last year, but there can be no underestimating Willis' impact and influence on the 49ers defense.

That influence is set to be even more important in 2014, and a big year from Willis in terms of game-changing plays could be crucial to helping this unit stay near the top of the league, despite missing two of its key men.

Final Thoughts

It is relatively obvious that the 49ers' replacements for Bowman and Aldon Smith are unlikely to produce the level of play that pair has consistently delivered during their time in San Francisco.

Yet what has seemingly gone unnoticed is that San Francisco has stacked quality depth up front this year and perhaps has improved its secondary following an overhaul. There is inexperience in the secondary, so a number of young players will need to step up and deliver pretty much immediately if the Niners are to make it deep into the playoffs.

But, while the defense has gotten younger, it still has a very experienced core formed by Justin Smith, Willis and Bethea.

Despite the losses of Bowman, Aldon Smith and Dorsey, there is enough quality and potential present for the 49ers to succeed in 2014.

The key to that happening lies with those remaining veterans—players who will be under increased pressure to lead the way and bring the best out of a somewhat depleted unit.

All statistics courtesy of NFL.com unless otherwise stated.

Nicholas McGee is a San Francisco 49ers Featured Columnist based in Leeds, England. Follow him on Twitter @nicholasmcgee24.