Originally Posted by Yooper
What is your crush like? Do you crush at home, or at the brew store?
+1 on this point.
I recently bought a used barley crusher and last Thursday brewed a Hop Stoopid clone. Best I ever got before was in the low 70's for mash efficiency, usually around 68%. Last Thursday attained 84% efficiency which I am attributing to both the crush and my improved fly sparging technique. I am convinced my grain after being crushed at the LHBS didn't look nearly the same as my crush last week, and the numbers I think prove it.
I don't know what flash sparge means but before I learned how to fly sparge I used to batch sparge. I'm pretty convinced you just can't get the same numbers with batch sparging as you can with fly sparging. That said you should absolutely get into the low 70s with batch sparging, maybe even higher.
I think the crush is a good place to start.