Just wanted to post an updated pic...had a chance to work on it tonight for a bit. Not a great deal of progress, but got some more coloring layers on his face. Once I get all the coloring set, I can go back and add the highlights and shadows and blend a lot of areas. Still a long way to go!
I know you said you weren't sure about adding a background to it... I really think having the infield diamond as a backdrop would work perfectly. That portrait just screams out to have the green and browns of the infield contrasting the shot of Harper. As if he's standing at home plate facing the crowd, that type of view of the infield. Then again, as already noted, I can't draw a stick figure, so its probably best to do the opposite of what I suggest.