There's a weirdness which bothers me about this sort of thing though, which is this: If you have such awesome accuracy and ability to toss a knife or shoot an arrow, etc. such that you can pin people to walls, hamstring them, etc. then you CERTAINLY have the accuracy to put one through their left eyeball every time!
I mean, OK, you can come up with some other explanations for some control effects, smoke arrows, a fusillade of daggers so thick the enemy is temporarily unable to get past it, etc. These rarely really provide the kind of paradigm that will support a whole class worth of 'stuff'. I see this as the main explanation for why there are 'off-role controllers' in Martial, like some rogues, some rangers, etc. It might actually be EASIER to imagine in terms of a melee character, but then you sink back into the swamp of "why is this not just a defender?"
TBH I think these are the considerations which lead WotC to never find any attempts at Martial Controller to be really convincing enough to adopt. MANY people pitched the concept to them! Yet they never bit.
Obviously I can't credibly contradict anything Mearls has to say about 4e and who, what, why things were the way they were, but IMHO WotC never cared that much about 'grid filling'. Maybe some people there were in favor of it, but I really don't see strong evidence that they were determined to do it, or that it was a big effort. In fact I think most of the 4e devs must have thought it wasn't a particularly strong idea and weren't that interested in it per se. They were certainly WILLING to fill in a 'gridpoint' if it resulted in a good class, but they were equally willing to simply allocate that concept to a more appropriate role/source if there was one, even if there were already a class in that 'slot'.
The few times they seem to have actually gone for it were NOT memorable! Who is excited by the Seeker? Ranged Primal Controller, weak concept that proved hard to translate into a good implementation!