The 49ers have undergone a head coaching change and have replaced both coordinators. After they hired Jim Harbaugh as the new head coach in San Francisco, Harbaugh surrounded himself with staff he was familiar with.
By bringing in Vic Fangio and Greg Roman, Harbaugh showcased his intentions of bringing in his own style of play. The moves lead to the assumption that there is more change coming in the near future. While it is unclear who will make up the 53-man roster, a more pressing matter to address may be what defense the 49ers plan on running.
The 49ers currently run a 3-4 scheme, occasionally dropping into a situational 4-3 defense. Defensive coordinator Vic Fangio has experience with both the 3-4 and 4-3 defense, but are the 49ers better suited to make the change back to the 4-3?
Harbaugh obviously seems like he would like to be in his current position for the long haul, and the feeling with management seems to mutual. Making the change could be a process over the next year or two, but the 49ers could very well begin the process this offseason.
Fangio transformed Stanford's defense into a 3-4, but may find himself reverting the 49ers back to the 4-3 that they had prior to 2007. Let's take at how the personnel in the front seven would fit into the new scheme.
Patrick Willis is far and away the centerpiece of the 49er defense. In a 4-3 defense, you need a stud middle linebacker who has the ability to play sideline to sideline. The defensive linemen in a 4-3 soak up the offensive line and give the middle linebacker room to roam. While it is unclear how the rest of the defense would react to being placed in a 4-3, Patrick Willis would likely flourish in the new scheme.
Takeo Spikes has exceeded expectations during his time in San Francisco. He may not have played at a Pro Bowl level, but he certainly sufficed as a backside middle linebacker alongside Willis. His best days appear to be behind him, and it is unclear how much he has left in the tank. Spikes would not survive the transition, as he is incapable of making the switch to outside linebacker.
The 49ers have not been successful at bringing in an every down outside linebacker. They have a rotation of outside linebackers who carry flaws with them, but suffice as acceptable as a whole. Even so, the 49ers outside linebacker position leaves something to be desired, especially in a 3-4.
The success of a 3-4 defense is largely predicated off the pass rushing abilities of a the outside linebacker. Manny Lawson was brought in because of his ideal build and speed for the position. He can seal the edge and isn't too much of a liability in coverage, but his pass rushing skills called for the 49ers to make Ahmad Brooks his replacement on passing downs.
Vic Fangio will be the best judge of evaluating the futures of Travis Laboy, Parys Haralson, Ahmad Brooks and Manny Lawson, as he will be able to see whose shortcomings could be potentially lost in the switch to a 4-3.
Navorro Bowman is being groomed to be the successor to Takeo Spikes. Bowman could be a natural 4-3 outside linebacker, which was his position in college before the 49ers moved him inside. If the 49ers moved Bowman back outside and retained Manny Lawson, the 49ers could succeed under Fangio.
Justin Smith is the 49ers' best pass rusher. He is relentless on the outside and plays at a high level for four quarters. In a 4-3, the defensive line takes on more pass rushing responsibilities. Smith could make the switch and see virtually no alterations in his game whatsoever.
The 49ers would need to bring in another defensive end. This year is a deep draft class for defensive linemen and the 49ers have the seventh overall pick. Grabbing an elite defensive end or defensive tackle in this draft is an attainable goal, especially if the 49ers choose to address the cornerback position in free agency.
The 49ers don't have any other defensive end on roster who would be an impact player in a 4-3 defense. The shortcomings of the defensive line aside from Smith played a large role in the regression the 49ers saw on the defensive side of the ball this year.
Aubrayo Franklin took the biggest step backwards in 2010 of anyone in the 49er defense. His play did not warrant an extension and with the new coaching regime in place, it is unclear if he will be franchised again—assuming the franchise tag exists after the CBA is renewed—and given the inconsistent state of his play this season, the 49ers may not adhere to his demands.
Defensive tackle would take precedence over all else in the front seven if the 49ers were to make the switch. Ricky Jean-Francois has been a nice addition and could eventually be a starting DT.
Isaac Sopoaga could move inside, as he has the size to do so. His play is average, but he could certainly be a rotational defensive lineman. Defensive line depth is critical, especially when you have four.
Everyone is looking for a guy like Ndamukong Suh to come in and wreak havoc in the interior line in a 4-3. The 49ers don't have anyone even close to that level, but could bring in a lesser talent to fill the void they see at this point.
The 49ers are two outside linebackers, a defensive end and potentially a nose tackle away from being a dominant 3-4 defense. Going to a 4-3 would require a comparable amount of change, but might not be too far of reach.
It may seem illogical to make the change at this time, but with the underwhelming performance of the defense this season, it appears it could be time gear up for a brief period of transition.