I understand where or why people think there is the same numbers of gaps. Take a 44 defense for example against 2 TEs and then against 2x2 look.

 

 

....E.T.G.C.G.T.E......

...E.....T.....T.....E...

.....B....B....B.....B

 

There are 4 gaps to each side of the center. You have 8 defenders for 8 gaps and 4 of those defenders have to cover a zone or a receiver. Your OLB or your DE have contain which in this case is D gap.

............W...............................W

..E....................T.G.C.G.T......................E

.............B.........E.T.....T.E..........B............

..C.......................B.....B........................C

 

In the two TE look there is a bubble over the C and T. In the 2x2 there is only a bubble over the C. The defense has been compressed due to the lack of a TE. To a defensive coordinator in the 2x2 look there really isn't a D gap. The DE still has contain so he is still responsible for the widest gap which in this case is C gap The LB has flat or man so by pass coverage responsibility takes away anything that goes beyond. The end of the line of scrimmage helps determine where your contain or force player plays. It is most common to count the number of gaps from contain in.

I'm sorry about the publish date. He spoke at the AFCA coaches convention in 78 on "air option" football.

Sorry I hit post before I finished so that didn't come across with the rest of the post. He also had a book which contained the offense he ran at Highlands which is pretty interesting. A movable back that would add gaps to the OL and could be used to trap and wham along with go out for the pass. Very creative stuff. The air option book you mentioned has some great stuff on how to isolate defenders