With NHL free agency officially opening last Friday, the Bruins got a jump on the holiday weekend by making two notable moves with their own defensemen on Thursday: They signed Torey Krug (four goals, 40 assists last season) to a four-year contract worth $5.25 million annually and, as expected, they bought out the final two years of Dennis Seidenberg’s deal which would have carried a $4 million cap hit for each season. This was the obvious choice since Krug is only 25 years old and just coming into what should be the prime of his professional career while Seidenberg is 34 with a litany of injuries suffered from the last few years.

The interesting stuff really started to percolate on Friday as the B’s made one of the biggest signings around the league by nabbing former St. Louis captain David Backes (21 goals, 24 assists in regular season and seven goals, seven assists in the playoffs) and agreeing to a five-year deal worth $6 million annually with him.

Boston predictably failed to re-sign its lone marquee free agent — right wing Loui Eriksson — who ended up in Vancouver with his fellow Swedes the Sedin twins on a six-year deal worth $6 million annually. Another former Bruin, left wing Milan Lucic, came to terms on a whopping seven-year contract with Edmonton worth $7 million annually. Backup goaltender Jonas Gustavsson (11-9-1, 2.72 goals against average, .908 save percentage last season) signed a one-year deal with the Oilers worth $800,000 so the B’s replaced him with a familiar face: Anton Khudobin (two years, $1.2 million annually) who played for Boston from part of 2011-13.

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Defenseman John-Michael Liles re-signed for one-year and $2 million, forward Riley Nash (two years, $900,000 annually), forward Tyler Randell (one year, two-way deal worth $600,000) and forward Tim Schaller (one year, two-way deal worth $600,000) are the other guys that the Bruins picked up on a very busy Friday at TD Garden.

You’ll notice that there were no new defensemen in this entire group (their most obvious need after missing the playoffs for the last two years) and while it’s true that St. Louis’ Kevin Shattenkirk and Anaheim’s Cam Fowler both apparently remain on the trading block, the more time that goes by in the summer, it’s harder to picture either of them getting moved before this upcoming season.

Backes is the crown jewel of this offseason for the B’s (at least so far) and he should fit in well with his new team and city. He’s an excellent two-way center that was an All-Star in 2010-11, he regularly is near the top of the NHL leaderboard in hits and he has represented Team USA at the 2010 and 2014 Olympics. Bruins fans will get a sneak preview of what they can expect as the Minneapolis native will be playing for the U.S. at the 2016 World Cup of Hockey which begins on Sept. 17 in Toronto.

Follow Metro Boston Bruins beat writer Richard Slate on Twitter: @RichSlate