Double Subverted: In front of Captain Smooth, Sgt. Rough emulates his calm captain, but as soon as he's gone it turns out the sarge is just another Drill Sergeant Nasty.
In a montage where each officer passes on a piece of bad news to his superior, we see that the Rough-Smooth-Rough-Smooth juxtaposition repeats itself all the way up the chain of command.
Rough gets a promotion to a higher rank and immediately acts like a soft-spoken gentleman, while Private Tough, who's pretty likable turns into a Drill Sergeant Nasty the second he gets promoted.
Zig Zagged: At first the captain is the rough one and the sergeant the kind one, but after the sergeant blackmails the captain into being compliant, the sergeant's sadistic urges go unchecked. Ultimately, the sergeant discovers that his original method produced better results and returns to it.
Enforced: "We want the Captain to be An Officer and a Gentleman, but that doesn't really work in the Training from Hell scenes, and might come across as ineffectual in action sequences. Let's make his underling more in-your-face."
Lampshaded: Upon meeting the sergeant, one of the unfortunate soldiers complains, "Why is it that all the good captains have such scary sergeants?"
Invoked: The captain thinks the men will be more inclined to obey their orders if they see a cool, collected, aloof "brain" handing them down and a loud, scary "mouth" dishing them out.
Exploited: A private jumps at an opportunity to work directly for the captain, hoping he'll have to spend less time in the presence of the sergeant.
Defied: "If any of you little worms have got a problem with my leadership style... If any of you think me and the cap are playing Good Cop/Bad Cop with you, you should know... I'm the nice one!
Reconstructed: Sergeant Tough is better at keeping his brash treatment of the men to limits that won't cause them to hate him. He's still unpolished and comes down harshly on insubordination, but he's also affable and fair.