Last year at 49er training camp, San Francisco General Manager Scot McCloughan told me the 2008 San Francisco 49ers would be employing a hybrid 3-4 and 4-3 defense. I still have the audio recording and article to prove it.

A Training Camp Facelift

Well scratch that idea now.

Hall of Fame Chicago Bear linebacker and San Francisco 49ers' head coach "Samurai" Mike Singletary wants an actual identity. Physical with an "F," I believe.

In order for this to be achieved, defensive coordinator Greg Manusky must stress 3-4 defense fundamentals and be creative with his defensive play calling to overcome the 49ers' lack of a playmaking free safety and solid pass rush.

The 2009 San Francisco 49ers' defensive personnel fit a 3-4 scheme and they should not deviate from this course.

The roster lacks two very large and athletic defensive tackles like a young Bryant Young or Dana Stubblefield and two somewhat large and very athletic defensive ends such as a Dwight Freeney or Osi Umenyiora to run a 4-3 defense.

These types of players are not salary cap friendly, extremely hard to find and it seems like there's only one or two outstanding defensive line prospects in each draft.

Differing from the 4-3, the 3-4 defensive lineman is used as a space eater allowing the more athletic linebackers opportunities to get to the football.

Defensive ends in the 3-4 tend to be close to the 300-pound mark like the New England Patriots' Richard Seymour or Trevor Pryce while nose tackles can weigh an excess of 310 pounds such as Shaun Rogers. The linebackers in the 3-4 scheme are expected to make the big plays.

The 3-4 inside linebacker must be strong in run support because there are only three defensive linemen matched up against five offensive lineman, so it is essential that they stack and shed the efforts of an unblocked lineman in the running game.

A 3-4 defense also employs two outside linebackers in a two point stance who appear to be rushing the quarterback.

This creates a disadvantage for the offensive linemen to correctly determine their blocking assignments before the snap, hindering the offense's execution. There will always be confusion regarding which linebacker(s) is rushing the quarterback at any given time.

These defenders are often called "tweeners," as they are in between the normal size of defensive ends and linebackers. Players like John Abraham are capable of playing both 4-3 defensive end and 3-4 outside linebacker.

The "elephant" position, used by the George Seifert's 49er defenses, was a hybrid position using a player that could both play linebacker and defensive end.

Former 49er Charles Haley was the first to be utilized in this fashion and Manny Lawson or Parys Haralson should be capable of doing the same for the 2009 49ers.

The 3-4 does have a glaring weakness. Three defensive linemen cannot reliably collapse the five offensive linemen pocket on the quarterback, so it becomes a struggle to constantly put pressure on the quarterback unless the three linemen are freakishly talented.

Traditionally, the 3-4 has struggled against the pass but the zone blitz was created by Pittsburgh Steelers' defensive coordinator Dick LeBeau as a solution to this problem.

In a normal blitz package, you have five or six defenders rushing the passer. The remaining linebackers and defensive backs often play man coverage which can leave a pass over the top a definitive possibility against the secondary.

Wide receivers in the NFL tend to be taller than defensive backs (Detroit Lion Calvin Johnson comes to mind) and win the one on one battles a majority of the time.

For the zone blitz to work, the athletic linebackers must drop back and cover an assigned zone. Since there are four linebackers, the opposing quarterback does not know which one of the four will be rushing him. Whichever linebacker rushes, the other three shift to fill in the zones.

Sometimes the defense will rush two linebackers on the same side, leaving two defensive tackles and two linebackers attacking three offensive linemen. The two remaining linebackers can quickly shift over to fill in the gaps left by the two who are blitzing.

A 4-3 defense seems best suited to stop the modern day pass happy NFL teams while the 3-4 defense is better geared to stop run based offenses.

The key to success with the 49er defensive unit is mixing up pass rushers and utilizing zone coverages like the zone blitz and Cover 2. This will confuse the quarterback and force the receivers to play a far more physical game than they are accustomed to.

In Cover 2, the key players in the secondary are the safeties because they have to cover lots of ground. The safeties are responsible for all vertical routes and have to keep all offensive players in front of them at all times.

The linebackers and corners cover the short routes, so the safeties are the last line of defense.

The corners cover the flats and their main responsibility is to bump the receiver inside and not let him get to the outside, which would make it much harder for a safety to reach the receiver if he goes vertical.

The corners usually cover the hook, curl and out route while the linebackers cover the hook and curl routes in their respective zones, as well as slant and crossing routes.

If the San Francisco 49ers were to ever run any plays from the "Tampa 2" playbook with any success, a top end safety like Bob Sanders would have to be acquired in the near future to complement shut down cornerback Nate Clements, hard hitting strong safety Michael Lewis and solid 14-year veteran Walt Harris.

A Cover 2 scheme is great to use against teams that don't have too many speed demons and rely on short to medium routes, such as a team that runs the West Coast Offense. However, every Achilles has his heel.

An effective way to beat Cover 2 is by having two receivers stacked on one side in a pro set formation and have them run a "10 Smash."

The outside receiver runs a hook or curl to draw the cornerback to his position while the inside receiver runs a corner route right behind the other receiver. The safeties may not have enough time to defend the pass if timed correctly and thrown with pinpoint accuracy.

Each player has a specific area of the field they are responsible for. If they make a mistake in coverage, the entire game plan is jeopardized because it creates a hole in the zone.

This is broken coverage and the 49er secondary would probably fall victim to this because they simply do not have the personnel to run Cover 2 coverage consistently.

In order for this defense to succeed in 2009, they must be strong in bump and run man to man coverage allowing the assigned linebackers free run at the quarterback to keep up with the more established passing attacks in the NFL. It is imperative the three front linemen beat double teams and collapse the pocket inwards.

Will this defense be physical with an "F?" Current personnel dictate this 49er unit will be fast and extremely aggressive. Maybe that's what the "F" means.

Let's take a look at what Mike Singletary and Greg Manusky have at their disposal.

LINEBACKERS

No. 52 Patrick Willis

Strengths: Has incredible instincts and is always around the football. Has blazing speed for an inside linebacker. Could potentially be a future Hall of Famer if his production continues.

Weaknesses: Can be overly aggressive and overshoot the play at times.

Best Fit: 3-4 ILB or 4-3 MLB

No. 51 Takeo Spikes

Strengths: Veteran linebacker that has good speed and is an excellent tackler.

Weaknesses: Is not as explosive as he was when he was younger.

Best Fit: 3-4 ILB

No. 56 Scott McKillop

Strengths: Aggressive defender with solid tackling skills. Could become into a serviceable player in the mode of a Derek Smith.

Weaknesses: Not very flashy and not very fast.

Best Fit: 3-4 ILB

No. 99 Manny Lawson

Strengths: The former collegiate defensive end has incredible speed and athleticism for a linebacker. Could potentially be an All-Pro if his development continues. Plays like former 49er Julian Peterson.

Weaknesses: Durability is a concern and also needs to work on taking better angles at the ball carrier.

Best Fit: 3-4 OLB or 4-3 DE

No. 98 Parys Haralson

Strengths: Extremely hard worker that shows a great burst at the point of attack. Recorded a career high 8 sacks last year.

Weaknesses: Not considered to be fast for his position.

Best Fit: 3-4 OLB

No. 53 Jeff Ulbrich

Strengths: Solid veteran still has a place on this team. Sure tackler with a good mind for the game.

Weaknesses: Relatively slow for a linebacker.

Best Fit: 3-4 ILB

No. 55 Ahmad Brooks

Strengths:Has all the talent and physical tools to be a starter in the NFL.

Weaknesses: Inconsistency.

Best Fit: 3-4 ILB

SECONDARY

No. 22 Nate Clements

Strengths: Shutdown corner that can eliminate the opposing team's best receiver. Has excellent size, speed and does not have a problem making tackles.

Weaknesses: Sometimes takes bad angles on deep plays.

Best Fit: Man Coverage or Zone Coverage

No. 27 Walt Harris

Strengths: Experienced cornerback whose career was revived in San Francisco. Good in man coverage and is capable of bumping receivers at the line.

Weaknesses: Age. Younger, faster receivers can burn Harris on longer routes in man coverage.

Best Fit: Man Coverage

No. 36 Shawntae Spencer

Strengths: Steady veteran serves as key defensive back in team’s nickel and dime packages. Has developed into a steady playmaker in the 49ers' defensive backfield.

Weaknesses: Durability is his biggest concern.

Best Fit: Man Coverage

No. 32 Michael Lewis

Strengths: Known around the league as the ideal strong safety because of his physical approach, size and strength along with his wide range. Hits hard and makes tackles consistently.

Weaknesses: Takes awkward angles at times.

Best Fit: Man Coverage or Zone Coverage

No. 26 Mark Roman

Strengths: Smart, consistent veteran who started 27 games at safety for the 49ers.

Weaknesses: Hasn't had a turnover in AGES!

Best Fit: Man Coverage

No. 41 Jimmy Williams

Strengths: Excellent speed and size for his position. Has all the tools to succeed and could develop into something special if he gets his act together.

Weaknesses: Spent the entire 2008 season out of football.

Best Fit: Man Coverage

No. 31 Reggie Smith

Strengths: Former All-American second-team selection as an all-purpose defensive back by The NFL Draft Report, adding honorable mention from Sports Illustrated. Good speed and size for a defensive back.

Weaknesses: Still a little bit on the raw side. Needs to learn coverages better.

Best Fit: Man Coverage

No. 38 Dashon Goldson

Strengths: Developing safety that earned valuable experience on defense as a rookie and is also a standout on special teams.

Weaknesses: Like with most defensive backs, his angles of approach could be improved. Isn't exceptionally fast.

Best Fit: Man Coverage

No. 25 Tarell Brown

Strengths: A natural playmaker. Extremely alert and quick cornerback that has good hands. Capable special teams player.

Weaknesses: Needs to rely on his ability and training rather than his catch up speed to get back into position.

Best Fit: Man Coverage

No. 28 Curtis Taylor

Strengths: Displays excellent burst of speed. Moves well laterally, aggressive, and physically beats down opponents. Covers a large amount of area on the field playing with a large degree of suddenness.

Weaknesses: Taylor's football abilities do not match his reputation. He is more athlete than football player.

Best Fit: Man Coverage

DEFENSIVE LINEMEN

No. 94 Justin Smith

Strengths: Versatile lineman that lined up at defensive end and defensive tackle in Mike Nolan's version of the defense last year. Has an always running motor and has great strength for his size.

Weaknesses: A bit undersized at 285 lbs to play defensive end in a 3-4 scheme.

Best Fit: 3-4 DE

No. 90 Isaac Sopoaga

Strengths: Has the ideal size and athleticism to play in a 3-4 defense. Considered to be one of the strongest players in the NFL. Has the tools to play at the professional level for a long time.

Weaknesses: Durability.

Best Fit: 3-4 NT

No. 96 Kentwan Balmer

Strengths: 2008 first round draft pick is a space eater with excellent strength and foot work. Has the size and physical tools to succeed in the NFL.

Weaknesses: Needs to shed blocks better. Seems to be out of position on potential tackle opportunities.

Best Fit: 3-4 DE or 3-4 NT

No. 91 Ray McDonald

Strengths: Versatile, instinctive lineman that saw extensive action on the 49er defensive line rotation as a rookie. Shows excellent quickness off the ball.

Weaknesses: A little bit on the smallish side at 290 lbs to be a 3-4 DE.

Best Fit: 3-4 DE

No. 92 Aubrayo Franklin   

Strengths: Large, active lineman with good technique and balance.

Weaknesses: Needs to learn how to beat double teams better.

Best Fit: 3-4 NT

No. 95 Ricky Jean-Francois

Strengths: Explosive and flashes dominance. Plays with good pad level, fires off the snap with a solid first step, then explodes through the gaps up the field.

Weaknesses: Easily knocked off balance by the first block and easily handled at the point of attack by opponents. Generally a one move lineman who must beat blockers off the snap.

Best Fit: 3-4 DE