The Stoke City striker will hang up the boots at the end of this season.
Carragher told the Daily Express: "It's strange when you move. Ian Rush left and came back a hero. I still feel sorry for Steve McManaman. People say he left for nothing. Well, you got him for nothing. Michael came for nothing. We got £8m. People say we could have got £20m.
"Well, the year before we got Markus Babbel for nothing. I was disappointed with Michael's reaction. He came back with Newcastle for the first time - 'Where were you in Istanbul?' Before Istanbul there was Cardiff in 2001 when Michael won the FA Cup for us. People were talking about it for weeks. That was the best thing that had happened to Liverpool in a decade since winning the league."