Beer Smith Question

Okay I have created a nice recipe in beersmith.

Its a 6.0 gallon batch. I am shooting for 1.050 starting gravity.

I have my grains all set to get me exactly where I want.

My question is this.
Why when I look at volumes and enter in gravitys if I actually hit those numbers does it tell me I have a 63% effieciency? I set my eff to 68% because I am thinking thats what Ive been getting but maybe I just dont know how to properly calculate it.

I hit my mash temps and batch sparge. I have a nice rubbermaid cooler with false bottom it keeps heat nicely. I feel like I use alot of grain to get good numbers.

usually it'll spit out the efficiency when you enter the "measured batch size" and "measured OG" in the design page.

I'd be surprised if you couldn't hit more than 70% with a good cooler and false bottom ....perhaps a sparging issue?