I know we get tired of the comparisons but Saban's pressers were literally "get out your popcorn" entertainment. He gave insight to his why, he could take a question and find a way not to answer it and get on whatever tangent he had already preconceived. Deboer answers the actual questions and as you said gives coach speak. He needs to understand he is at the highest profile job in all of sports in America. Showing his personality and enthusiasm for the team, game, and what his plans will be will only help him with the fan base and the team.
What he needs to do is win. Winning covers a multitude of sins. He'll get a pass this season because of the obvious, but patience won't be a long leash after this season. Winning cures everything in sports.

