That's tough. Do they fit in the calf area? Usually when that kind of gapping happens it means the boots are too high rather than too tight, but you are tall so I can't imagine you would have that problem, leaving me to believe that they were meant to look this way. If they are fitted in the calf area, that would further compound my suspicion that it is just the style of the boot, because it means someone whose knee area could fill out the boots would probably find them too tight in the calves.
What is the style name? I'm curious to read reviews of them on Zappos (if there are any) to see what others had to say.
Either way I kind of like them. They definitely have a funky look to them.