I like Liles. I think he's our best option in the starting PF. It doesn't mean he needs to play 20-25 minutes but he can do it depending on the opponent.
Liles provides spacing and not only because he shots threes but because he can put the ball on the ground and finish or pass decently. There is zero problem if he is not getting the ball because the starters are making all the shots, he keeps playing defense and rebounding. At the same time, he's shooting more and more confidently when needed. He runs the court well and finishes correctly in fast break. Usually gets some offensive rebounds, facilitating good second options for the team.
Defensively, he does his job. He can't stop an all-star one on one, but he has good concentration, positioning and fundamentals so he's not a liability like Forbes. He's not too athletic but he's not too small or too slow and he has good basketball IQ, which balances the overall. He works well under the boards, rebounding or boxing out.
Trey Liles probably isn't a starter caliber player in the NBA but he's a serviceable player that fills well the starting PF in our team. The starting line up needs to get rid of Forbes and all the stats will get better. Every player sharing the court with Forbes hurts his numbers. I don't see any problem on Liles playing 15 minutes, 6-8 at the starting the 1st and the 3rd and even some 4th minutes if the game is going well for him.
I would rather trade/sell Gay than him, the value/salary is much better in Liles, who could fit very well in the second unit for a much lower price. Thinking on addind a true starting PF to this team? You need to look at Rudy's salary. Trey Liles is doing very well on his first season in San Antonio. For a bag of peanuts.
Samanic? I love him but he needs time. Metu? Might be an option but not ready to start at all yet. I hope he has an opportunity during the season beacuase of injuries/rest. We shall see then.