Pickford, Walker and Maguire were only half a season and started pretty much every game. Not indifferent at all, quite impressive in fact.
None of those loan spells were indifferent but that's besides the point anyway. All they represent is half a dosen players who have made it at this level since about 2010. Sure there are more but there are ten times as many who haven't.
I want him to be good enough, I honestly do but I just don't see it. He had one 70 yard run against a tiring Liverpool defence, 3 years ago but watch that video again; how many players actually tried to tackle him? Zero, Wijnaldum sort of runs near him at one point but that's it. It was good but hardly Owen/Argentina good.