John McGinn has many qualities and can fit into many roles in midfield, but that box to box role is something he's become accustomed to for pretty much his whole club career. Between St. Mirren, Hibs and Villa, that's been his main role. His never-ending energy and his constant pressing is something he's become known for.
With Scotland, McGinn plays a different role. One that utilizes all of his ability more offensively. McGinn is often Scotland's highest midfielder. Sometimes even mirroring a #10 role, McGinn's ability to press the centre-halves and goalkeepers from a higher starting position has lead to many goals for Scotland. Add in the fact he's a good finisher and moving him higher up the park seemed a no-brainer for Scotland.
I also think it could work even better for Villa. Today, despite losing 3-0, we watched Villa dominate for 45 minutes, and McGinn causing the Chelsea back 3 chaos. This came from Watkins being back up top, and McGinn having more freedom to roam. Both McGinn and Watkins have some of the highest pressing stats in the league, so to combine that pressing, again, seemed a no-brainer. It caused the European Champions a problem, it would definitely cause other teams in the league bigger problems.
Another thing to note is McGinn has tailed off a lot in terms of goals recently for Villa, whilst still remaining Scotland's talisman. This could help add goals from midfield to his game, and Villa's game simultaneously. The question is still out there as to who should be the deeper lying midfielders for Villa, however I think McGinn deserves the chance to be pushed forward for a prolonged spell.
Smith has a conundrum to figure out where the likes of Watkins, Ings, Bailey, Traore, Buendia etc all fit in, its a plethora of riches going forward, with more depth defensively, it's still a promising season.
They will need time, they will need patience, but the talent is there, and despite the doubters, Smith has improved Villa season after season. The signs are all there for him to do the same this year, but with the number of changes over the summer, it won't come immediately.