Kind of had the thought of using whips: tangle someone up to Prone or Immobilize, and then Pull them. Add some Sonic damage burst attacks from cracking the whip, maybe Deafen or Daze as you get stronger. Give it a class feature to make whips do damage, and increase its range as you go up tiers. Sure, whips don't work that way, but if I can have a guy that shouts at people to replenish their HP because he's so courageous, I'll make a shot at having a guy that can whip from farther away because he's good with whips. I don't know if there's enough in there to remain relevant all thirty levels, but there's room to start.
But, uh, returning that to the idea of applying it to an existing class, uh... Rats. I really want to say, "Take a Fighter, drop Combat Challenge, Combat Superiority, Heavier Armor proficiency, and 3 surges per day (so 6+con). Add Whip Training, increase whip damage to 1d8, twice per encounter whenever you [land an attack with a whip weapon whatever the verbiage would be that would allow this to apply to melee basic attacks and powers with the weapon keyword while wielding a whip] you may choose to add Pull (Wis min 1), Prone, or Dazed EONT to the attack, and an at-will power that lets you make a Burst 1 in range of your whip that does 1d6+Wis sonic damage. Avoid selecting powers that aren't controller-y." Thing is, part of what makes Fighters the unofficial martial controllers, is their Defender capability, so it might come out as an even worse Controller than just rolling an unmodified Fighter.
And yes those Controller abilities should scale with tiers I'm just trying to keep things condensed because I have zero experience in mid or high level play.
But, uh, if you're just concerned about the Controller role as printed, well, someone at Wizards believes Hunters are Martial and Primal Controllers...