Look at their stats. If you trade him for Jamison, you're trading Deng for an inferior player who does the same things. The scoring stays the same, but you lose a couple rebounds and an assist. It'd make no sense for you. You clearly need to switch things up. You've only won assists once, you clearly need help in the area. He'll help your FT%, which you haven't won, as well. If you look at it, Jamison only averages 3 more rebounds than Felton, while Felton averages 6 more assists than Jamison. You'll be losing some scoring here, yeah, but that's not your biggest need.