Stan, you'll be surprised,my friend,how many 737 drivers doesn't know or doesn't care how the trailing flap works on the 737.
I know there should also be a change in drag,I guess you can't modify lift only,but this change is minimal,that's why B doesn't even mention it.
Sorry,but I have problems remembering the english terms to explain more from an aerodinamical p.o.v,but I guess you know already what I am talking about.
Brgds
Alex