When I got this, I was dismayed that there was such huge gap between the two sides in the back, and was afraid I'd measured or used the sizing chart incorrectly.  But don't panic!  Make sure you follow the try-on rules (no lotions, perfumes, etc.) just in case, but go ahead an lace it up and try it on.  First off, there's a great 4" panel in the back (not typical on cheaper versions) that covers the gap between the two sides (beneath the laces).  Second, once you actually get it laced up and tightened it'll probably fit a lot better than it initially appears (I got down from a 6" gap that looked hopeless to a gap that was entirely covered by the flap).  Third, it's leather:  it'll stretch over time, so you want it to fit a bit snug at first.