I believe Horner can play in a few different positions, so probably viewed as a useful utility player to have as part of the squad.
Rules for the U20's (now called the Development League) have changed to allow 5 players over the age of 20, so there's a bit more scope to work with players that are a little older to bring them on.
Under TB we had quite a bit of divide between the younger lads and the "first team" when it came to training etc. Yogi does things very different and views them all as part of one big squad with everyone training together far more regularly. One of the main reasons we're seeing the true potential of these lads, IMO.
I think the benefits of that have been apparent all pre-season. Even today we didn't have what we might consider our strongest/preferred starting squad, yet we looked in control and comfortable for the vast majority of the game.
If you work on the premiss that the other team can only score when they have the ball...and we limit that possession...then logic dictates that you'll concede fewer goals and in turn, lose fewer games. You then build on that and look to turn that additional possession into additional chances and the logic follows through to dictate that we should win more games.
We've got the first bit in place and are building on the second part. Having seen all but one of the pre-season games, there's been a progression in terms of how direct we're being when getting into the final third and that will continue to improve.