Not every player to come through the Manchester United academy will have long careers at the club, but many end up thriving elsewhere. Kobbie Mainoo is on the fast-track to stardom after establishing himself as a key player in midfield for the Manchester United first team, and this past week he starred on international duty for England too. Mainoo’s rise to prominence has seen him overtake some of the players he would have once looked up to. In the case of Teden Mengi, the young defender might yet catch him up. Mengi left Manchester United last summer to sign with Luton Town, and has enjoyed a…