The English midfielder has replaced Pierre-Emile Hojbjerg as captain after he stated his desire to leave the club.
"He took this news very professionally," Saints' manager said.
"He knows with his attitude and his passion that he quite the role model for how we want to play and how we want to live in this club.
"That's why it was an easy decision for me to say, 'Right, this guy shows everything that Southampton is about'.
"I think he's asking for more responsibility and he's getting it now.
"I'm sure he will be a very, very long-term big captain that is for the whole squad like Pierre was also.
"Hopefully, it doesn't have a negative impact on his game, but I don't think so.
"More responsibility doesn't mean that it's all down to him on the pitch. Everybody has the responsibility and they must take this. That will make us a better team."