We’re now in the back half of training camp with three preseason games down, three to go and just nine days before opening night at TD Garden. The opening night roster is beginning to come into focus, but Monday’s (at Philadelphia) and Tuesday’s (vs. Washington) preseason games will offer one more opportunity for a stock-boosting audition. Thursday’s preseason finale against the Rangers at Madison Square Garden will be a dress rehearsal for the 2023-24 season.