He isn't 23 - and I don't think it's anything to do with that.
He's in poor form and only he can play himself out of it. He was good vs Boro and did what he needed to do - for some reason he's regressed again in the last few days, though worth noting in a side that played poorly on both occasions.
Think the reason he was good against Boro mate was that he kept it simple, he needs a run of games where he keeps doing that, build his confidence up, and then I think we'll see the real Barkley again.