The latter half of your post is incredibly condescending, especially for posters like myself to read who've watched our youth and u-21's, u-18s, and before that, reserves on mutv every game for years and years now, the reason I'm not particuarly optimistic over him is simply the fact we've seen so many other's who've dominated in the past at that level, with primary attributes to stand out being pace and power fail to take the next step up, we only have to look at some of Tunnicliffe's one man team, marauding performances, who went on to win our player of the year award despite having talents like Pogba and Morisson around him yet fail to make the step up.
When I watch Janko the past few games he's mobile yes but he beats his man often with just pace alone, his balls across more often resemble Valencia esq smacks into areas rather than pin point precision pick outs, he's more developed than some others at this point, but personally I'd rate a few in the squad as having a higher potential for the next level when all's said and done.
The commentators on MUTV seem to adore him every time he touches the ball and our coaching staff seem to like him, we'll see what happens but please don't dismiss my post with "probably just seen a youtube clip" becuase it's pretty harsh.