Yesterday we went 4 downs with the 49er offense, today Fooch from Niners Nation returns to go 4 with the Niner defense.

You can check out my 4 downs over there.

The defense seems to pretty solid against the pass, led by a solid pass rush, but the 49er run defense has struggled. Why?

First off, the pass rush is not quite as solid as you might think.  The 49ers did manage to sack Matt Cassel 5 times last week, but this was one time where sacks do not provide a sufficient measurement.  When Cassel wasn't getting sacked he had all day to find his open receivers and at times was able to pick apart the 49ers on short passes.  As for the run defense, the 49ers have gone with what they call a "Big Sub" defense.  The defense usually consists of 4 defensive linemen, 2 linebackers and 5 defensive backs.  It creates a bend but don't break style of defense to prevent the big play.  The problem is that running backs have eaten up the interior of the defense.  The per rush average is not huge, but they get big rushes when they need them.  The problem for the 49ers defense lately, aside from the rush defense is that big plays have in fact been happening, which sort of defeats the purpose of the entire defense.  I wouldn't be surprised if Desean Jackson got free deep for a big touchdown.

Mike Nolan is a defensive guy, so three years(4 seasons?) into his tenure as head coach how do you rate the overall progress of the defense since he took over?

The talent on the field has improved by leaps and bounds.  While the 49ers did shell out a ton of money for Justin Smith and Nate Clements, both have paid off rather nicely up until recently.  Smith has seen time at 6 of the 7 DL/LB positions and Clements has been a mostly very solid corner.  However, the pass rush has remained a weakness.  When Nolan came in his goal was to transition to a 3-4 defense eventually, once they had enough linebackers.  The problem is they don't use the 3-4 as they originally planned.  The Big Sub mentioned above has been used considerably but is clearly not doing the job against good offenses.  I expected the defense to be a strength, but the last few weeks have not been pretty.

How are our old Eagle pals Michael Lewis and Takeo Spikes faring in San Fran?

It took Spikes some time to learn the defense and you could see the early struggles.  However, the last couple of weeks he's been about as good as we could possibly expect.  Against the Patriots he finished with 14 total tackles and got his second interception in as many weeks.  Patrick Willis is the playmaker on defense, but Spikes has made some big tackles.

Michael Lewis has flown under the radar in his 1+ seasons with the 49ers, but he's done exactly what they need.  He may not be a great safety in the passing game, but his support in the run game has been solid.  Of course the fact that running backs are making it to the second level for him to get the tackle is not the best thing in the world.  Overall, I've been quite pleased with his performance to date.

The Niner defense actually has quite a few names most of us are familiar with... Willis, Clements, Lewis, Spikes... but who is a guy we don't know now but may know by the end of Sunday?

The guy on defense to keep an eye on is Dashon Goldson.  Goldson was great in training camp, pulling down an interception or two every practice.  He has been pushing Mark Roman for the starting free safety job but couldn't quite nail it down.  However, in using the Big Sub defense, Goldson gets on the field fairly often for a second year safety.  His production in camp has not translated to regular season action, but I think he's on the verge of busting through.

Thanks again to Fooch from Niners Nation