Roos was strident in his criticism of the Swans' first half against Freo after they trailed by 32 points at the long break en route to a 37-point defeat.
"I think he's made it pretty clear that our attack on the ball and our endeavour has got to lift," Kennedy said before training on Wednesday.
"It's been found wanting the past few weeks and that's disappointing, but it's something that can be turned around pretty quick with the right processes.
"You always go out there and try to win but it was evident in some of the replays that we just weren't switched on as much as what we perhaps have been.
"Against a quality side like Freo, or Hawthorn this week, they're just going to cut you up."
Swans recruits Mark Seaby, Daniel Bradshaw and Shane Mumford have all faced their former clubs in 2010 and Kennedy will have his turn on Sunday when his side tackles a rejuvenated Hawks outfit at the MCG.
Kennedy's history with his old club runs deeper than most. His grandfather, John Kennedy, won four best and fairest awards at Hawthorn before coaching the club to its first three premierships, while his father, John Kennedy Jr, won four flags during a 241-game playing career.
However he said his family's history with the Hawks would mean little on Sunday.
"Obviously the last few weeks have been pretty disappointing and we need to try and find that thing that makes us win, and that's the main thing for us this week," he said.
"It's not really about me or [fellow ex-Hawk] Ben [McGlynn] or my history with Hawthorn. It's about us trying to get another win on the board.
"It's no different to me than anyone else who supported a different club growing up. Now I'm very much a Sydney Swans man and I hope to be for a long time."
Kennedy did concede that old Hawthorn habits had died hard in his family, despite his new allegiance.
"I'm sure they'll be supporting the Swans but I'm sure there will be a few members of the family that might be hoping for a draw," he said.
"[My grandfather] is very supportive of me, but he's a Hawthorn man through and through.
"I do have a little cousin up here who's very much red and white. Dad's taken a little bit longer to come round but they're very supportive."
