Shape - not only are they all different shapes, but they're all different sizes. This will ding you in both appearance as well as (possibly) tenderness. With chicken, it's hard to make sure you're hitting tenderness with all pieces if they are not all the same starting size/weight. We weigh all our chicken before we trim them, then again after we trim. We group them into three categories according to that: large, medium, and home eating (too small). Then when we cook we will do two pans, one of each of the two sizes. When we select for the box we try an ugly one from each size to determine what goes in the box.
Sauce - as was mentioned above, try dunking your thighs instead of how you applied here. The bottom left two are a lot darker than the others, and the top right is very uneven.
I don't mind the color on any of them (the bottom right two may be a tad darker than we would look for). Work on shape/size and dunk in warm sauce next time and I think you'll be on your way! BTW, it took us forever to figure out how to shape/size thighs...don't give up if you have a hard time getting it right for awhile.