Mr. Rozier was born to play for the Celtics. Need proof? He was born on St. Patrick’s Day. Need further proof? Just watch his game. In limited minutes at the end of last season, he was a defensive waterbug, hounding opposing guards. Now entering his second season, the 22-year-old appears to have made offensive strides and is being counted on to replace Evan Turner, who left for Portland. If he can prove to be an effective ball handler and a good 3-point shooter, he might end up being the team’s best all-around guard. Bonus: He’s under team control for many seasons to come.