Lawn Woes

I think this is my third spring in Cambridge, but this year the grass in the back yard decided to play dead.  Really dead.  It actually looks like someone intentionally killed it all.  Or the vast majority.  The "front yard" is still fine.  As is most of the side between the deck and the fence.  There's also one corner in the far back that is still growing (surprisingly, this is the spot that Nuke favored last year, all winter and all spring). 
I'm doing what I think I can to help encourage the green to come back.  So, I made the following changes for this year.  First, I changed fertilizers - the early spring was a Scott's crabgrass preventer blend that is made for this time of year.  If nothing else, I'll have less of the crabgrass that took over at the end of last year.  Today, I picked up a weed & feed at Mahoney's - this will likely go on tomorrow (weather permitting).  Second, I aerated the lawn using one of those manual aerators (does 2 plugs at a time).  In some spots it seemed like the soil was extremely compacted - I'm thinking this might be part of the problem as Nuke and I may have compressed the dirt too much for the grass to grow.  And, finally, I am now bagging the grass clippings instead of mulching.  This seems counter to all that I've read, but I figured I'd keep up with the fertilizer for this year so the bagging would eliminate any chance of the thatch being the cause of the problem.
There are a few scattered tufts of grass in what was once barren.  Hopefully I can coax them into filling out the remainder of the lawn.  If not, I'll likely take drastic measures in the fall (or spring) and attempt to reseed a big portion of the yard.