Meanwhile, Smalling is said to be interesting Arsenal boss Arsene Wenger as he looks to improve his defensive options.
Parker urged Van Gaal to sign Hummels and believes United could sell Smalling and Jones to help comply with Financial Fair Play rules.
“Van Gaal will be heartened by Borussia Dortmund centre-back Mats Hummels’ recent statement that he wishes to widen his horizons by playing outside the Bundesliga,” Parker said.
“The German is the right player for United as he would be an organiser in the Nemanja Vidic mould.
“United should go all out to get Hummels in the summer as I believe his pairing with Marcos Rojo at the heart of the defence will flourish.
“The World Cup winner will also get the best out of Jonny Evans.
“Both defenders are saleable assets – they are young England internationals who should attract attention from many clubs.”
We don’t know who Parker has been watching this season but if anyone is going to be sold by United in the summer it will be Jonny Evans and not Smalling or Jones.
Evans has been poor or average in almost all of the games he has played this term while the departures of Smalling and Jones would leave the team dangerously short at the back. The whole point of signing Hummels will be to give van Gaal some quality depth at the back given the fact he has had to blood youngsters Paddy McNair and Tyler Blackett over the course of the campaign.