The Celtics do have a potential ace in the hole in a $28.5 million trade exception acquired in the Hayward sign-and-trade. Internally, though, there are mixed feelings about using it before the March 25 trade deadline. The Celtics are high on Harrison Barnes, sources told Sports Illustrated, the Kings forward who could be moved by Sacramento. There’s interest in Jerami Grant, too, though the Pistons have not shown any urgency in offloading the 26-year-old Grant, who is having a career season. The Celtics could also hold onto the exception and use it in a deal this offseason, before it expires.