When Jaylen Brown dropped off a pass to Xavier Tillman Sr. in the corner during Game 3 of the NBA Finals, Dallas completely ignoring the Celtics big man, it recalled another moment earlier in his career with the Memphis Grizzlies. Where the conversations surrounding his jump shot began with a former Duke player and Memphis assistant named David McClure. “Even though he was a bigger body and he didn’t shoot that many (threes) in college,” McClure told Boston Sports Journal this week. “His mechanics were in a place where he might not be a go-to shooter, but that he could be a very, very serviceable, consistent shooter as long as he got his confidence up of letting it go …”