Last season, David Quinn inherited a blue line comprised mostly of aging veterans and inexperienced youth. Quinn was charged with the task of programming the Rangers into playing with increased discipline and structure, intelligent puck management and stronger net-front defending.

Rome wasn’t built in a day and that was clear during Quinn’s first season behind the Blueshirts’ bench. The stretches where the Rangers played sound team defense were intermittent. Part of the reason is the growing pains that come with youth learning on the fly at the NHL level. Another factor was the lack of an A-1 defenseman leading the group.

That missing piece was acquired this summer in the form of Jacob Trouba. The 25-year-old has established himself as an all-situation, minute-devouring defenseman who drive offense and excel in the shutdown game.

Trouba’s arrival was one of several significant offseason changes to the back end. Highly-touted former Harvard standout Adam Fox has also been added to a remodeled right side. Fox earned praise for the poise and ability to create offense at the collegiate level. He flashed hints of his ability during an impressive showing at the Traverse City Tournament.

Though the NHL represents a major jump in terms of speed and quality of opposition, Fox is expected to make the Rangers’ opening night roster and be an important part of Quinn’s defensive revolution.

The additions of Trouba and Fox along with returnee Tony DeAngelo crowded the right side and forced Jeff Gorton to exercise a buyout of Kevin Shattenkirk. Injuries prevented the 30-year-old from meeting expectations during a disappointing two-year stay at The Garden. Fellow right-hander Neal Pionk was included in the trade that brought Trouba to New York.

Currently, DeAngelo is without a contract ahead of Friday’s training camp start. Quinn and the Rangers are hoping that once he’s signed, the 23-year-old will continue the positive trends of last season.

On the left side, Brady Skjei is the favorite to skate alongside Trouba on the first pairing. The 25-year-old didn’t play the best hockey of his career over the past two seasons, though some of the reasons could be attributed to playing with revolving defensive partners.

Skjei clearly has the ability to mold himself into a quality, all-around defenseman. Skating on Trouba’s left side is going to give him the chance to take major strides forward in his fifth season.

Elder statesman Marc Staal has long served as a key presence in the dressing room – but is far removed from his best days as a premier shutdown man. It will be interesting to see how Staal fares in the new season with a new defensive partner. The Staal-Pionk pairing of last season could kindly be described as leaky.

Staal and Brendan Smith survived the threat of buyouts. In Smith’s case, it’s unclear if he will begin this season at The Garden or in minor-league Hartford. Libor Hajek and Yegor Rykov are among the prospects pushing for a chance to make the opening night roster.

Overall, the Rangers as a defensive unit must improve on some key statistics. Last season, the Rangers ranked third-worst in the NHL with a -381 shots on goal differential and their 3,958 shot attempts against was the fourth-highest in the league. Their penalty kill ranked 27th overall with a 78.2 percent success rate.

Given the offseason improvements and a year of Quinn’s teaching under their belt, the Rangers’ blue line corps must show significant progress in the attack, in transition and when protecting the fort in the new season.

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