I was out with a client of mine the other day and she had a question about short boots (they are so ON trend right now). She'd tried a number of different styles on but just hadn't found a pair that looked right...but why? After trying a pair of mid calf Frye's on for me my suspicions were confirmed. What the issue was..she has very nice muscular legs. The mid calf boot was hitting her mid calf (huh go figure) which was hiding the shape she has in her leg from the calf down which caused her leg to look thicker than it should.
What would look best on her leg was a true ankle boot. This would hit lower on her leg, therefore allowing the curve from her calf to her ankle to show thus allowing the shape of super nice legs to show.
Remember, this look, either the mid calf or the ankle, are best when worn with a skinny pant. This boot adds visual weight so you want to balance it out with something more narrow.