Last week I threw out my semi-rational irrational prediction that Vernon Davis would make the Pro Bowl this season.  Originally that was just going to be a one-off post with nothing to follow.  However, there are plenty of things I think will happen in the coming season that are just as rationally irrational.  So, this series will become a semi-regular piece for the rest of the offseason.  I can't really tell you how many I'll do or how often, but more when the mood strikes me....as it is has today.

During the first two seasons of the Nolan era, the 49ers defense has been less than stellar.  According to straight yardage statistics they were 26th overall in 2006 and 25th in 2007.  Using DVOA, Football Outsiders ranked the 49ers 28th in 2006 and 26th in 2007.  At first glance the improvement does not seem all that big considering the big splash in free agency in 2007.  However, 49ers fans realize how much time they had to spend on the field and how worn down that made the defense.  So it's safe to say, statistical improvement by the defense will be helped in part by an improved offense.  However, I think the defense itself will improve of its own accord for several reasons.

Manny Lawson
Lawson missed most of last season after tearing his ACL and his impact was certainly felt.  The defense was forced to adjust on the fly at outside linebacker and it just never worked out.  Lawson is an impact player and how he bounces back from surgery will play a big part in how this defense improves.  If he is not tentative and doesn't lose a major step, I'm going to be a pleased 49ers fan.  While I don't know if Manny Lawson could be the next Julian Peterson, he can still be a great linebacker for the 49ers.

Justin Smith
Smith seems like a prototypical Nolan player in the way he grinds it out and busts his ass.  Smith practiced quite a bit at outside linebacker and will be one of the more flexible players on defense.  Tully Banta-Cain is better served coming off the bench and a reduction in his playing time will help improve the defense.  Moving Smith around the field will force the offense to work a little harder trying to keep track of him.

Ray McDonald
This will fall more in the irrational side of things.  I have this feeling that Ray McDonald is going to have a very solid second year.  While he may not become an all-around threat, I could see him turning into a legit pass rush threat.  When the team goes to the 4-3 on occasion, or when Smith is at OLB and McDonald is at DE, I just see McDonald bringing some quality speed off the end.  Anybody else agree?  Maybe think I'm insane?

Secondary
Aside from the drafting of Reggie Smith, the secondary is pretty similar to last year.  I consider that a good thing.  Dashon Goldson seems to be stepping up as a potentially key backup at safety.  Although Walt Harris is aging, Shawntae Spencer remains a talented back up and Tarell Brown will provide strong competition at the nickel back.  There is always talk about the chemistry on the offensive line and how important that is for its success.  I think one could argue the same thing about the secondary.  When a corner is on an island, he's often expecting some kind of backup deep from the safeties.  I think the longer a unit is together, the more cohesive they become and the more they trust each other.

A lot of this comes down to the pass rush and I can honestly say I don't know what to expect there.  If he's healthy, the return of Manny Lawson is practically like a whole new player.  Combine that with Justin Smith and I am definitely getting excited about the 49ers 2008 defense.  While I'm not expecting one of those dominant Ravens or Bears defenses, I do expect good things.  A prediction of top 16 does not seem entirely out of the realm of possibility.  I had thought about predicting top 10, but I'm not quite sure if they'll make that leap yet.