The 33-year-old defenseman waived his no-movement clause for the trade to Nashville (45-30-7), which qualified for the Stanley Cup Playoffs for the eighth straight season but was swept in the Western Conference First Round by the Colorado Avalanche.
"The first thing that stood out to me was I think where [Nashville] is competitively," McDonagh said. "Anybody that's played Nashville knows the group they have there and how they've made the playoffs and [how they're] trying to be a contender to win the Cup. As a player, you want to be a part of teams that have a chance to win the Cup.
"When Nashville showed interest, it was right away a big point for me to realize that this group is competitive and has all the pieces that I believe you need to win a Cup. You look through their lineup and they've got all the pieces and great character guys, guys that have been in the league that have a lot of experience, mixed in with some young guys, too, and a great coaching staff."
McDonagh, who has four seasons remaining on a seven-year, $47.25 million contract ($6.75 million average annual value) he signed with the Lightning on July 1, 2018, had 26 points (four goals, 22 assists) in 71 games this season while averaging 22:27 of ice time per game, including a team-high 3:15 while shorthanded. He also led the Lightning with 137 blocked shots and was fourth with 96 hits.
McDonagh had five points (one goal, four assists) in 23 playoff games for Tampa Bay, which advanced to the Stanley Cup Final before losing in six games to Colorado.
"Ryan McDonagh is one of the best defenders in the NHL, a selfless player and a great leader," Lightning general manager Julien BriseBois said. "I would like to thank him for everything he's done for us, including working with me to facilitate a trade this week.
"Considering each player's age, position and contract, I came to the conclusion that Ryan was the odd man out."
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Lightning forwards Ondrej Palat and Riley Nash, and defenseman Jan Rutta can each become an unrestricted free agent on July 13. Myers, Anthony Cirelli, Mikhail Sergachev, Alex Killorn, Corey Perry and Erik Cernak are among the players whose contracts expire after next season.
"I don't have anything new on the Ondrej Palat or Jan Rutta front," BriseBois said. "I will be talking to their agents in the coming days, that was already planned. Obviously, we have more cap space after this trade than we did before, but I don't have any new information as it pertains to those two players and being able to sign them to new contracts.
"More importantly we freed up some cap space for 2023-24 and beyond, which I'm hopeful will allow us to secure the rights for Anthony Cirelli, Erik Cernak and Mikhail Sergachev for years to come."
McDonagh played parts of five seasons for the Lightning after he was acquired in a trade with the New York Rangers on Feb. 26, 2018, getting 99 points (20 goals, 79 assists) and a plus-74 rating in 267 regular-season games. He is third in Lightning history among defensemen in playoff games (89), assists (21) and points (23), helping them win the Stanley Cup in 2020 and 2021.
"I could obviously talk for hours about the group there and all the memories and whatnot," McDonagh said. "There's no doubt winning your first Cup, that feeling we had, so many guys on the team there that have been through a lot together. Losing in the first round together [to the Columbus Blue Jackets in 2019], getting swept and then finding a way to come back and win the Cup.
"Like I said, a lot of the first time feeling there, nobody can take away. To be able to go through those long days in the bubble (in 2020) and stick together as a family, it's pretty incredible. That will be a lasting memory for sure. It's been an incredible five years and looking forward to utilizing all the experience I've had on the losing side and the winning side to hopefully do something special with the Nashville group."
With the Predators, McDonagh will join a back end that includes Roman Josi and Mattias Ekholm. Josi had 96 points (23 goals, 73 assists) in 80 games this season, the most by a defenseman since Phil Housley had 97 points (18 goals, 79 assists) for the Winnipeg Jets in 1992-93, and was a finalist for the Norris Trophy, narrowly losing to Cale Makar of the Avalanche.
"[Josi] is one of the premier defensemen in the League," McDonagh said. "He's just unbelievable to watch. When you play them, he just seems to be all over the ice at all times. So just to be able to be on the same side of him now is going to be a thrill, and Ekholm, too, has been a huge piece there for Nashville."
Video: Lighting trade McDonagh to the Predators
Selected by the Montreal Canadiens in the first round (No. 12) of the 2007 NHL Draft, McDonagh has 337 points (71 goals, 266 assists) in 783 regular-season games with the Lightning and Rangers. He also has 64 points (12 goals, 52 assists) in 185 playoff games, which is fourth among active players (Zdeno Chara, 200; Perry, 190; Joe Thornton 187).
"Ryan McDonagh is the ultimate team player who will bring experience and leadership to our lineup," Predators GM David Poile said. "A former captain of the New York Rangers, a two-time Stanley Cup winner and four-time Stanley Cup finalist, we couldn't be more thrilled that he waived his no-movement clause to come to Nashville. With the ability to play in any situation, he immediately strengthens our defensive corps."
Myers had four points (one goal, three assists) in 27 games this season, his first with the Predators after he was acquired in a trade with the Philadelphia Flyers for defenseman Ryan Ellis on July 17, 2021. Signed by Philadelphia as a free agent on Sept. 21, 2015, Myers has 33 points (seven goals, 26 assists) in 142 regular-season games, and four points (three goals, one assist) in 16 playoff games.
BriseBois said the Lightning are not considering a buyout of Myers' contract, which has one season remaining at $2.55 million.
"No, our plan at this point is to work with Philippe Myers," he said. "We've liked him going back to his junior days. We really like his tool box. I've liked him in Philly. For whatever reason things didn't work out for him at the tail end in Philly and in Nashville last season.
"He's only 25 years old, he's a 6-foot-5 (210-pound) defenseman with size and some physicality. He's a quality skater. He can improve his skating. In the past we've been able to work with players and provide them with resources to become better skaters. He has a huge shot. We think there are enough tools there that intrigue us enough to work with him and see if we can't help him reach the potential we saw in him not too long ago."
Mismash has yet to make his NHL debut after being selected by Nashville in the second round (No. 61) of the 2017 NHL Draft. He had 12 points (six goals, six assists) as a rookie for Milwaukee in the American Hockey League this season.
NHL.com independent correspondents John Glennon and Corey Long contributed to this report