This isn't some kind of revelation that Pogba is most suited to the left side of a midfield 3. It's the position he played his best football for Juventus in. I can't see Mourinho deploying this formation or tactic however. I think it's obvious that the 4-2-3-1 is the formation that Mourinho sees as the long term solution. Mourinho has played Pogba in a midfield 2 most of the season, giving him further defensive responsibility. Considering how inept Pogba looked on the defensive side of things against City at OT, I think his improvement since then has been extremely encouraging. I can see Pogba becoming a great complete midfielder in that role.
People bring up the fact that Griezmann and Pogba didn't work together in the Euros last year, however I think Pogba has worked on his game a lot this season, and is much more defensively competent and positionally disciplined because of it.