I don't know, but Lemar looks like one of those playmaker that starts from wide but tends to move and play centrally, rather than the likes of Perisic, Moura, and even Dembele that tends to stay wide more. I may be wrong, but he looks more suited to those attacking midfielders that play for Arsenal. A Pires instead of a Giggs.
I believe United already have that type of players in Mata, Micky, Lingard even at lesser quality. With the rumour of Perisic, I think Mou looking for a different type that would stay wide and provide both pace and width.