He has more than enough quality needed for the games he would be used in. Bottom half teams in the league when the team needs rotating, League Cup, FA Cup depending on the draw, the odd Champions League game results in the group permitting or even starting Europa League games if t came to it.
The way the transfer market is going, and the money we have, teams are going to want an arm and a leg even for squad players, so why spend upwards of £20m for somebody to sit on the bench when we have our own more than capable of doing the job when required?
Debatable to be honest because Lingard has been used in many big games this season by Mourinho. We all know he seems to favour those work hard, so in that sense he has been picked a lot of the time ahead of other players.
He can do a job... kind of.... just not a very good one... if you want an attacking player who can fill the space and not offer much going forward I guess he's good.