(Kris Russell battles for positiong with former Bruin Reilly Smith during a Bruins-Flames game in March 2015. Photo by Joe Makarski, Bruins Daily)

And then there was one.

After the first major flurry of free-agent defensemen signings since July 1, the UFA market remains slim along the blue line. The highlights so far are Dallas’ Jason Demers signed with Florida and Dan Hamhuis fled the Canucks to take Demers slot with the Stars.

Last year at the trade deadline, Calgary shipped its No. 3 D-man, Kris Russell, to Dallas for a mid-level draft pick, knowing cap space with mega deals coming for Sean Monahan and Johnny Gaudreau would keep the Flames on the UFA sidelines with Russell, despite his modest $2.5 million salary.

And a big payday coming for one reason: the aforementioned 2016 shallow pool of Unrestricted Free Agents.

While the Kings’ Luke Schenn is still out there, it’s Russell who the Bruins should be in hot pursuit. Their likely competition is Toronto that desperately needs blue-line anchors to keep their rebuilding on pace in the Eastern Conference. Where they – along with non-playoff partners Columbus, New Jersey, Buffalo and Carolina – have improved their stake in the 2016-17 outcome. And all likely more than the Boston Bruins thus far.

Does anyone think Montreal will be out of the playoffs with a healthy Carey Price and their blue line reinforced with Shea Weber and no P.K. Subban distractions?

Here are 10 reasons why the Black and Gold need to put the right green on Russell, who is likely sitting — and smiling — somewhere near his fax machine in Alberta, while his agent sends along the most recent of many offers.

* Russell made a base salary of $2.5 million the last few years. He will command at least double that in the current market. The Bruins would likely need to pony up at least $35 million for a 6-7 year deal. With all of the projected roster signed for next year, the Bruins have almost seven million in current cap space.

* The need to fit Russell into the long-term deal coming for Brad Marchand works, given any combo of factors, starting with Zdeno Chara who has two years left at $7 and $4 million, respectively. Marchand can get his $7 million per year after this season with the Bruins adding the Chara savings of 3 mill to his current 4. And/or not protect a 40-year-old Chara in the expansion draft next June, and adding his salary to increase cap space for 2017-18.

* Russell played his career in the deeper Western Conference and mostly with the Flames who play in the competitive Northwest Division. He also played under two good coaches in Bob Hartley and Lindy Ruff. He is 29 and at his peak the next several years.

* Russell was No. 3 on the Flames roster behind captain and perennial Norris-Trophy candidate Mark Giordano, and T.J. Brodie. Russell’s departure puts Dougie Hamilton at No. 3 in Calgary. The Russell dollars will be comparable to Hamilton’s, while Russell would automatically become at least No. 3 on Causeway Street.

* Russell is among the very best shot blockers in the NHL.

* Russell comes with a few concerns. He’s not that big at 5-foot-10 and 170 lbs. But he can skate and played an average of 70 games the past few years. Two seasons ago he played 79 games with a 4-30-34 scoring ledger and a plus-17. All while Giordano missed half the season with a torn bicep, and the Flames made the playoffs for the first time since 2008-09. This past season, mostly with Calgary and its goaltending woes, Russell played a total of 62 games with 4-15-19 and a minus-5.

* Russell carries the label of his line getting out-possessed on many of his shifts. But the Bruins experience and depth at center, and its breakout systems in the tad-slower Eastern Conference should help to remove that label.

* But Russell takes some of the concerns about the Bruins overall defense off Tuukka Rask’s shoulders. Rask, who had the highest goals against average in home games, did a good job for as long as he could publicly defending his defensemen breakdowns. Starting the season without Russell and with the same complement on D as the group that ended last April puts Rask and the organization behind the 8-ball from first puck drop.

* Russell is a veteran. Claude Julien likes to work with veterans over the kids. Russell will benefit from Julien as his coach. With veteran David Backes, Julien gets two dependable guys out of the gates on offense and defense, especially with David Krejci and Torey Krug questionable for healthy starts after surgery a few months back.

* Russell averages a half a point a game in his 36 career playoff games and hails from Caroline, Alberta. A Boston signing would be Sweet, eh?