Through four games it's readily apparent that the biggest weakness of your 2008 San Francisco 49ers defense is the pass rush, or lack thereof.  The only time we've seen a legit pass rush was the first half of the Cardinals game and most of the Lions game.  The Cardinals adjusted in the second half to shut down the rush and the Lions...well they're the Lions.

The secondary certainly deserves a share of the blame for yesterday's debacle, but I think most of us can agree the lack of pass rush opened up the deep game.  If you look at the Seahawks game, when Hasselbeck had time he picked apart the defense even with subpar wide receivers.  Even with all the injuries, the Saints brought a better crew of receivers to the game (damn you Lance Moore!).

To this point the most prolific pass rushers have been Parys Haralson, Justin Smith and Roderick Green.  In yesterday's game the most interesting play came when Patrick Willis blew through the line and took down Drew Brees as he was passing the ball.  Up to this point much of the discussion has centered on further development of Manny Lawson as a pass rusher.  Well, what about Patrick Willis?

If we were running a traditional 3-4 I'd understand the role of Bamm Bamm and Takeo Spikes in the defense.  However, since the team is using a non-traditional hybrid defense, why not expand Willis's role in the Mike position and alter Spikes's role in the Ted?  Patrick Willis finished 2007 with 4 sacks.  Based on general observations over his brief 20-game career, when the defense runs he closes in on the running back and when the defense passes he drops into coverage fairly often (please correct me if I'm wrong).

He is clearly an athletic freak who can make plays in virtually any situation.  And he's not the Vernon Davis non-performing type of freak.  So, why not mix him into the pass rush a little more when you're running a 4-man front.  Takeo Spikes is an established veteran middle linebacker who still has enough athleticism to make plays (see yesterday's interception).  Why not let him roam that middle of the field and take advantage of Bamm Bamm's athleticism?  I'm not saying have Willis rush the QB on every play, but I think it's an option that could be further explored.

I said in the offseason I thought this could be a very good defense and I still believe that.  However, as long as the pass rush is relatively non-existent, the rest of the defense will be held back.  I need to go back over the video of the game but Ray McDonald is one guy who has flown under the radar through much of the first four games.  He is a guy that I think needs to be a playmaker for this defense.  Aubrayo Franklin has shown improvements at times, but is still clearly not the answer at nose tackle. 

It's time for Greg Manusky and Mike Nolan to get creative.  The 49ers schedule is packed with quality quarterbacks that will make things a living hell.  Even a guy like Matt Cassel could end up looking like Tom Brady if he gets all day in the pocket to find Randy Moss.  So, any other ways to improve this pass rush?