I forgot to add that I added a gal. of boiling water before the mash runoff, so the total volume of water into the mash was 7.5 gal. Still, though, I noticed a lower than usual absorption. I did not correct volumes for temp., but the volumes I measured were at no more than 150F. There shouldn't be much difference in that, should there?
That makes things a little more realistic. I put the numbers you gave me into my spreadsheet, I assumes 83% extract from the malt and 4% moisture content. Note the error analysis on the side. I took the liberty and made a guess how accuate your nunbers are.
Were the 1 gal that you added to the mash part of the sparge water volume? If no then your grain absorption is aboput 0.13 gal/lb. This is typical. If yes, your grain absorption is 0.07 gal/lb. This is significantly less and the cause of your high batch sparging efficiency. At least the problem of the conversion efficiency being lower than the efficiency into the kettle is solved. You had me questioning my theroy for a moment.