I've always thought that our coaches have both of these players playing out of position. To me, it would make much more sense to move Martin to WR, and H Lee to RB. The running styles of Martin and Lee are completely different. Martin is a "scat back" type who relies on his speed to get around the corner or into open space. Moving the quicker Martin to wide receiver would automatically give him more open space to work with, and make him a potential "big play" option. From the WR position, if Martin beats only one guy, he can take it to the house.
On the other hand, Lee is a stronger player than Martin (I always heard that Lee is one of the strongest players on our team!), and --in my opinion-- has a more durable body. With Lee at RB, opposing defenses must respect the run. Play action becomes very effective with Lee in the lineup at RB.