Do you believe that he is playing below his capability?
Not really. I think he lacks the personality to assert himself, and the longer that pattern gets ingrained, the harder it's going to be to change. He needs a year in the G League, probably, to beat up on people and post 30 and 15 every night. And we know that that won't happen.
We should probably see if it does before making a firm decision that we are going to trade him. That's all I'm saying.
It's theoretically possible that he could have such a great year that the Suns will be desperate to keep him, but I think the chances of that are vanishingly small. (I propose keeping him until the offseason and pursuing a sign-and-trade with a team willing to gamble on his alleged potential.)
One way to think about it is, "Are the Suns ever going to fear facing this player on an opposing team"? With the other recent big-man busts of Len, Bender, and Chriss -- maybe I'm missing one -- it was clear that, even if the player ended up finding his way to competence, he was never going to be someone who could hurt you. Len has fashioned himself into a decent role player, but no opposing coach has ever said, "Okay, here's what we need to do to handle Alex Len."
That's how it is with Ayton. The only way opponents need to plan for him is, "When his teammates try to force-feed him with lob passes, here's how you make that a likely turnover." Other than that he is no weapon at all. He does have some impact on the defensive end, and once in a great while he makes a real difference there, but it's too rare an occurrence to get excited about.