That's Big-12 mentality, a 57th ranked defense is considered very good. Maybe they're better against other hurry-up offenses (though they did give up 57 against La. Tech). They also gave up 28 to Sam Houston State, and 29 to Missouri.
Teams that run this type of offense have never been known for their physicality. See Texas, Oregon, Arizona, West Virginia, and yes...even Oklahoma. Last year the A&M defense was #59, and that was in the Big-12. This year in the no offense SEC they were #57. Their m.o. was to outscore people...not overpower them. Playing tough, physical football and scoring lots of points are two different things. No one is discrediting A&M, but these teams don't hold up well against physical teams...we've all seen it, many times in the past. Sometimes the truth hurts.