Carrick is central to United's sweeping ball movement - whether it's launching a counterattack, or switching play to the outside channels when he joins the midfield line when they're pressing forward.
Rooney & Ronaldo grab the headlines and deservedly so, but Carrick is their pivotal 'passing playmaker' even though he's a defensive-minded midfielder by trade. Outstanding player and imo there's no chance Man United will let him go, at least until he's well into his twighlight years ala Roy Keane - fitness permitting of course.
I reckon they prefer Hargreaves tbh