I've never been a fan of 4e, and even less of the "role" concept. 5e is better for dropping it.

That said, the issue of a martial controller always puzzled me. All the other "power sources" had a class for each role (in the pre-Essentials books); but there didn't seem to be a martial controller.

Someone at my local FLGS 'splained it to me: the archer ranger was supposed to fill that niche. Specializing in distance attacks, it does the most toward battlefield control.

Like I said, not a fan; but that was my understanding.