Sewell said both Mitchell and Luke Hodge were admired and respected by all at the club.
"We've got two exceptional leaders at this club and we're very fortunate to have that. They both complement each other very well," Sewell said.
Sewell criticised Brereton for suggesting Mitchell was not as popular among his teammates as Hodge.
"I don't think we've seen Dermott at the club for three or four years so I'm not sure where he's getting that information from," Sewell said.
Sewell said it didn’t matter who was the captain as both were crucial parts of the Hawthorn side.
“It is just a term, a label - the 'c' next to the name. It’s not going to change anybody’s actions or the way they behave at all. I think it’s null and void,” Sewell said.
Sunday’s comprehensive defeat of Carlton was the Hawks’ second consecutive win.
Sewell said there was no one factor that changed overnight, rather the win was the result of tinkering with the game plan over a period of time.
“There are things we’ve been working on, not just in the lead-up to the last couple of weeks but we’re starting to see the results of the work we’ve put in over the past couple of months,” he said.
“Things are slowly starting to turn our way and we were probably a little lucky to get over the line last week. As we keep improving aspects we are going to get better.”
Sewell said the most noticeable difference between Sunday’s game and Hawthorn’s patchy early season form was a renewed aggression.
“One of the most important things we saw coming out of the weekend was the attitude and guys hitting hard and initiating contact,” he said.
“You guys (the media) like to use the unsociable football term so much and it is something that maybe we’ve been lacking over the past few weeks and it was certainly something we brought back yesterday.”
