Southampton have got some of the best running stats and have one of the highest presses in the league, a lot of that is down to him. Having another player in the team like McGinn would really wear opposition teams down.
If we did sign him though, I would start believing the speculation that we've not been impressed with Sanson and that we'll be looking to move him on.
Having Ward-Prowse just sit in front of the defence would be a waste so we would still need someone of that type if we did get him IMO.