Seems like the zombies are getting slower each season.
My girlfriend noticed that too. She also pointed out that in season 1 they looked almost human, almost. Now they look a lot more decomposed. Is it possible that since they are dead and decomposing, eventually they will just fall apart and be gone?
Another something to think on. Do zombies breathe? Since they are up and walking around I assume their muscles work. Don't muscles require oxygen to function, thus requiring blood flow, thus requiring a working heart? If this theroy is correct, wouldn't a heart or lung shot incapacitate a zombie? Maybe not kill it since the brain is what comes back to life, but immobilize it. Just something to think about.