What do you base this on? He's been deployed as a wide forward/winger in Mou's first two games in charge. Has netted twice and assisted twice.
Not sure where you get that he wants to use him as a wingback. The fact that Ben/Rose is expected to stay further back means that Son will not have to bomb home as much as previously as well.
Actually, Son netted once and assisted twice after Mou. Aurier, who is a definitely wingback, netted once and assisted once after Mou. Thats why we cant figure out only based on stats.
Rose hardly did overlapping, and Son should have focused on defense. I think Mou wants defense from Son not attack. I mean that's a wingback.