I just don't really see how he fits on this team.
Harkless is basically an athletic wing defender and that's about it. He is no threat as a scorer, he's an average rebounder, and his passing numbers are about on par with Avery Bradley (i.e. terrible).
To make matters worse he can't even fill the Avery Bradley "3-and-D" role because his career 3PT accuracy of 31% makes him a non-thread from outside. His career three throw accuracy of 59% is even worse.
I can totally understand other teams taking an interest in that type of player it they need that type of role filled, but don't we already have enough players in the "athletic defensive guys who can't score" mould?
I understand people are looking at this guy for potential, but even then there is a distinct difference between potential and pure youth - he might be young, but is his potential really that high? Looking at past history athletic prospects who are average rebounders, poor passers and have limited scoring ability have rarely ever amounted to much in the league. In fact I can't really even think of one such player who has ever become anything significant.
I can see the comparison to Jeff Green (defence, athleticism, average rebounding, poor passer) but there is one MASSIVE difference between those guys - Jeff Green has always been a capable scorer. Over his first three years he averaged around 15 points per 36 minutes which (combined with his defence and athleticism) is enough to get you a role on a team.
Honestly, I'd rather stick with Crowder, Turner and Young. Turner is better than Harkless now, Young (IMHO) has far higher upside, and Crowder we already have and pretty much fills the same 'athletic defender' role and is already on the roster.