One of the longest trade sagas in the NHL is finally over as the Senators sent superstar defenseman Erik Karlsson to the Sharks on Thursday. In the deal, first reported by TSN, Ottawa receives center Chris Tierney, defenseman Dylan DeMelo, winger Rudolfs Balcers, center Josh Norris and draft picks for Karlsson and forward prospect Francis Perron.

In addition to the four players, the Senators will receive at least two picks, and possibly as many as three. They’re getting the Sharks’ first-rounder in 2019 or 2020, depending on whether San Jose makes the playoffs next season, and whichever is higher of the Sharks’ two 2019 second-round picks.

They’ll also receive a 2021 second-round pick if Karlsson re-signs, and that pick is upgraded to a first-rounder if San Jose also makes the 2019 Stanley Cup Final.

If the Sharks end up flipping Karlsson back to an Eastern Conference team like they did with Mike Hoffman, they’ll also have to send a first-round pick to Ottawa no later than 2022.

Karlsson, a two-time winner of the Norris Trophy as the NHL’s top defenseman, has one year at a $6.5 million cap hit remaining on his contract before he’s eligible to hit unrestricted free agency in 2019. The Senators didn’t want to risk losing him next year without receiving anything in return, so they’re moving him a year early for a haul to bolster their rebuild.

However, the package appears underwhelming for the Senators given the player they’ve giving up. Tierney, 24, set a career-high with 40 points in 82 games with the Sharks last season. DeMelo, 25, has recorded three goals in 133 NHL games.

The two prospects they’re receiving are among San Jose’s best, but not among the league’s best. Neither one was named to The Athletic’s ranking of the NHL’s top 100 prospects entering the 2018-19 season.

A player of Karlsson’s caliber being on the move is a rarity for the NHL. The 28-year-old is widely considered one of the best defensemen of this generation and he has the statistics, hardware and highlights to prove it. For the Sharks, his acquisition is a game-changer that could alter the course of their franchise, much like Karlsson’s departure will shake the foundation in Ottawa.

The Senators have been undergoing changes lately after off-ice issues shook their locker room. Hoffman, one of the team’s most productive forwards, was dumped to the Sharks, who quickly moved him to the Panthers. Other moves could also occur in the coming months as GM Pierre Dorion tries to remodel the team while limiting costs for ownership.

Karlsson entered the NHL as the No. 15 overall pick in the 2008 draft by Ottawa. He made his Senators debut in 2009 and won his first Norris Trophy two years later at age 21. Since then, he’s won another Norris Trophy (2015) and finished runner-up twice (2016-17).

The Sharks can now boast a defense that includes Karlsson, Brent Burns and Marc-Edouard Vlasic, which gives them strength from the blue line they lacked in previous seasons. Fantasy hockey owners will surely be circling around San Jose with two of the game’s most productive defenders playing on the same team.

The next contract for Karlsson is going to be a massive one. P.K. Subban leads the way for NHL defensemen with an annual cap hit of $9 million, but he’ll be surpassed next season by Drew Doughty’s $11 milllion average annual value. John Carlson and Oliver Ekman-Larsson, two players not at Karlsson’s level, recently signed extensions worth $8 million and $8.25 million annually, respectively.