Dowell has a great footballing brain for someone so young and his game always seems to go up a level when he plays with the first team. A lot of that is down to getting most of his first team opportunities against weaker opposition but I also think he benefits from the intelligence and movement of the senior players. At the U23 level, there are only a few players who are fully on his wavelength, like Davies and Walsh, but that number goes up with the first team which makes the game easier for him. I think this explains some of his "inconsistency" at the U23 level: Dowell relies a lot on his teammates' movement and understanding of the game and those things are erratic in younger players, as you would expect.
I hope he continues to play this summer. Dowell might not be in Koeman's plans for the upcoming season but he deserves the chance to show what he can do linking up his senior teammates, especially Rooney, Klaassen, and his good friend Davies. That's where his true quality is going to reveal itself.