The genious of that well-attached inner panel is that it is wide enough not to gap if the buckles are set on their largest setting, for a bigger calf, but narrow enough that the shaft shouldn't wrinkle or fold much with the addition of an extra hole, and extra tightening, for a skinny calf.
And speaking of ankles -- the Boomer measures 11" around at that point.
I do think the back buckles make this a slightly trendier riding boot than the other Sesto style I reviewed, the Boyle, but the lovely lean line is not going out of style anytime soon. Can see this one with cute summer sundresses, minis, possibly even cutoffs, as well as the jeans and sweaters those of us in the still-frozen tundra continue to wear.
Calf slimness: ****/5 with buckle holes as is; *****/5 with another hole added per strap
Well, I can't anymore, as of June 2018 - let me know if you do!