Button/By S. Bradley

Over the next couple years, we should witness a changing of the guard on the Bruins’ back line.

We might look back at this upcoming weekend as a crucial time once that transformation happens.

The Bruins will hold their Fifth Annual Development Camp at the team’s Ristuccia Arena practice facility in Wilmington, Mass., Thursday through next Monday. Among the defensemen scheduled to attend are 2011 first-round pick Dougie Hamilton, 2007 second-round pick Tommy Cross, 2009 third-round pick Ryan Button and former Boston University standout David Warsofsky.

With Hamilton carrying the best pedigree into this camp, this is by far the best collection of defensemen, in terms of NHL potential, to attend one of these summer get-togethers for the Bruins. At No. 9 overall, Hamilton is by far the highest-picked defenseman selected in the draft since Peter Chiarelli took over as general manager, topping Cross (35th) and Button (86th). Warsofsky, who was acquired by the Bruins via trade at the 2010 draft, was the 95th overall pick by St. Louis in 2008.

The draft is supposed to be the lifeblood of the organization, but so far Boston has replenished its back end through trades for other team’s prospects and free agency. After trading Mark Stuart and Matt Hunwick last season, the Bruins won the Stanley Cup without a defenseman on their roster or among their “Black Aces” that was drafted by the organization.

Looking beyond the 2011-12 season, Joe Corvo and Johnny Boychuk are due to become unrestricted free agents, while Adam McQuaid and Matt Bartkowski could be restricted. Andrew Ference is signed just through 2012-13, the same year Steven Kampfer’s entry-level deal expires. The Bruins could have some holes on defense coming up, so with an uncertain future in terms of the Collective Bargaining Agreement, the development of players like Hamilton and Button into NHL top-six guys will be vital.

Development camp is usually an opportunity for recently drafted players to get a feel for what life at NHL training camp will be like and for returnees to show how much they’ve progressed not just with their skills but their makeup and maturity. So Hamilton, Cross and Button, as well as the others, will report with different goals this weekend. They might want to forge some bonds, however, because they could be playing together in the not-so-distant future.

The Bruins won’t be able to rely on other teams to raise their defensemen for them for ever, and 2011 development camp turn out to be the period of time when some of the better blueliner prospects took a huge step toward replenishing the defense depth chart.