He doesn't utilize his teammates to their optimum on offense,
He doesn't have an impact on defense.
He's a ball dominant scorer.
And the league has won with them, but they have been far far more dominant and better than Melo,
You won't ever win anything with Melo as your main player.
Phil is smart enough to see this. That's why he put him on the block. However Melo's trade value is so crap, teams won't even give up theie 3rd best player for him. No Love. No Blake or DeAndre. That should tell you all you need to know about Melo's value in the league.
Great individual scorer. That's where it starts and ends. If you appreciate 1 on 1 moves, and losing, you'll love Melo. If you appreciate teamwork and winning, you'll see Melo has to go.