text: Jamie Peacock, Kevin Sinfield and Kylie Leuluai ended their rugby league playing careers with the 22-20 win over Wigan Warriors at Old Trafford, which completed Leeds' domestic treble.
  "I do believe it gave us an edge," McDermott told BBC Sport.
  "For Kylie, JP and Sinfield to go out on that note, that is fitting as well."
  Speaking after the win, which attracted a Grand Final record crowd of 73,512, McDermott added: "Everybody wanted to tip in, that was the difference."
  For Sinfield, the longest serving of the trio, it was his final game in the 13-man code before switching to rugby union's Yorkshire Carnegie, starting next month.
  The Leeds and former England captain admitted it was an emotion-charged send-off.
  "It was joy," Sinfield said when asked what it felt like to finish as a treble-winning captain.
  "Thankfully the guys jumped on me and hid a few of the tears. They were tears of joy. It was an unbelievable way to finish."
  The defeat marked the end of Wigan full-back Matty Bowen's career, while winger Joe Burgess also said farewell as he joins Sydney Roosters.
  Bowen, who scored a brilliant solo try to put Wigan 18-16 ahead in the second half, said it was a "surreal" occasion, having become a father for the third time just before midnight on the eve of the game.
  Daughter Tatum was in the stands with the rest of Bowen's family, 16 hours after being born.
  "It's been a busy two days at the hospital... we've had a beautiful little girl," said Bowen, who will take up a role with former club and newly crowned NRL champions North Queensland Cowboys as part of their community coaching team.
  "She is healthy, that's the main thing. We haven't told anyone, for nine months nobody knew. I surprised my mum two weeks ago.
  "I just want to relax now and enjoy time with the family and watch them grow."
target: Leeds Rhinos were given a decisive boost for the Grand Final by the emotion surrounding their departing trio, says head coach Brian McDermott.