Missed pre-boil by quite a lot

This was my first all-grain BIAB after a few mini-mash BIAB beers that went well. Made a dunkelweizen with this grain bill:

5.5 lbs raw red wheat (breiss)
1.5 lbs munich 20l 2-row
1 lb. malted rye (breiss)
4 oz special b
4 oz chocolate malt (lhbs didn't have carafa ii)

Mashed in at 154 on the button at 1.25 qt/lb for 60 minutes. Lost about two degrees.

Then heated 2 gallons of water to 168, pulled grain bag and let it drain, then put bag into 168 degree water for 10 mins. Lost about 10-12 degrees over that time.

Gathered 4 gallons of wort (which was my goal) but only 1.052 SG when I was shooting for 1.068.

The question: did the sparging step cause the low SG due to the drop in temp? I squeezed the bag as much as I could after sparging, just didn't hit the gravity. Boiled as usual and just topped up enough water to hit my post-boil gravity regardless. Got about 4 gallons in the end at 1.052 SG.

I don't know what you planned your efficiency to be, but I can't figure out how you were expecting 1.068. I punched in a 4 gallon batch with 75% efficiency with the grain bill and got 1.058 on 2 different pieces of software. If you got 67% efficiency, then you would be inline with 1.052.

I have done BIAB a couple times and I plan on 65% and go from there. I am sure it will work out either way, but maybe double check where the 1.068 came from.

Math came from BeerSmith2. Water volumes were adjusted for my equipment and so forth. Thinking now that the crush wasn't fine enough and/or mash wasn't long enough. Trying this recipe again in a few weeks with some tweaks.

I do have my shop double crush my grains, so that might be something that will help you out in the future. I would imagine that the temp changes didn't have that much of an effect. I don't sparge, so I can't speak from experience.

I let the mash go for 90 min in my smaller test batches. Makes a big difference. Beersmith actually suggested a 90 min mash for my BIAB recipes.

How is that much wheat going to convert? You need malted barley (base malt) to convert. Very odd recipe IMO, or perhaps an error of sorts???

edit...I'm guessing you meant 5.5 lbs munich, and 1.5 lbs wheat, NOT vice versa???