The Celtics are the sleeping giant of this upcoming NBA offseason. Boston was pegged as a true title contender entering the postseason this year after a shockingly successful regular-season campaign , but flamed out dramatically in the first round, blowing a 3–1 lead to the rival 76ers . The early postseason exit was a failure that fell on the shoulders of all the key members of the organization—and president Brad Stevens was clearly not happy about it. Speaking to media for his end-of-season press conference, this season’s Executive of the Year openly stated the roster must improve to fix the issues he’s observed on the floor the past few playoff runs . Specifically Stevens mentioned finding players who can put better pressure on the rim to create higher-quality shots on a possession-to-possession basis. The Celtics’ recent history of aggressive offseason maneuvering would suggest these comments precede an eventful summer in Boston.…