Most of the classes I took seem to think the crossed arms is a shielding movement. Guarding what they say, or want to say. They are holding something back or not telling all. I expect with Coach Saban he is not telling everything he knows.
The movements are not a 'Tell All', some people use the shield nearly all the time. The solution is to watch and listen to them and see if the Shield suddenly goes up, or does it all the time. It'a like a Polygraph examiner asking several questions to check the response, before he ask the 'Got You Question'.