To save money of course and in the same time to imitate some transfer action...
How would it save money?
In the form of not paying any money [if a straight swap as suggested], attracting a player and releasing one. Thus, no transfer fee, offsetting wages and showing the fans that they are working on new recruits. Outcome: Same numbers, no outlay.
So they can say that they've attracted a new body, but in fact it's a freebie [sort of]. Most probably, Rout's wages are higher than these of McWhatever guy.
How would it offset wages? This lad will probably want more than Routledge is on.
McGugan wouldn't make our first Xl. In fact, he wouldn't make the bench if we were to get another couple of atttacking players in. I'd rather take a couple of million from Routledge's sale and put it towards a player we do need.