The 26-year-old Germany international centre-back is reportedly a summer target for Premier League giants Manchester United.
According to The Daily Mail, United manager Louis van Gaal is interested in signing the 2014 World Cup winner in the summer transfer window.
It has also been claimed by the British newspaper that Dortmund will “ask for around £36m for Hummels”.
While Fjortoft is a fan of the former Bayern Munich man, he does not believe that the German is worth £40m.
If #mufc think Hummels is the answer, there is something wrong with their question— Jan Aage Fjortoft (@JanAageFjortoft) April 11, 2015
Hummels good player when he is "up for it" - doing too many mistakes. Class going forward - but defense for a defender important too...— Jan Aage Fjortoft (@JanAageFjortoft) April 11, 2015
Hummels had a good World Cup. But his partner, Boateng, a lot better now. Maybe Hummels needs a new club to make next step— Jan Aage Fjortoft (@JanAageFjortoft) April 11, 2015
Maybe! Think he needs a new challenge. Been weak lately https://t.co/eiOwzXZN7t— Jan Aage Fjortoft (@JanAageFjortoft) April 11, 2015
Is Hummels better that #mufc defenders? Probably Is he a £40 mill player? Not for me! If a Club wants to pay that. All the best— Jan Aage Fjortoft (@JanAageFjortoft) April 11, 2015
Hummels is one of the best centre-backs in the world, but this season he has struggled to maintain his usual great performances.
The 26-year-old is a ball-playing centre-back who likes to make attacking forays, but his knack of making tackles high up the pitch has cost Dortmund dear on occasions this campaign.
The German made crucial mistakes against Bayern Munich and Borussia Monchengladbach in the Bundesliga this month, and Dortmund lost both those games.
However, Hummels remains a superb centre-back, and one bad season should not tarnish the reputation that he has built for himself over the years.