The Pistons have been a busy team this offseason, upgrading their talent and various obvious needs that culminated with bringing back Chauncey Billups. But despite having 16 players on the roster, counting their three draft picks this season, Pistons president Joe Dumars isn’t yet done shopping. “The only thing left is trade possibilities, and that door will continue to be open,” Dumars said. “It’ll continually stay open.” As for the rumor mill that’s linked the Pistons with point guards Brandon Jennings (Milwaukee Bucks) and Rajon Rondo (Boston Celtics), he coyly debunked both reports — which had Brandon Knight as the common denominator as trade bait. “Bogus, bogus. No conversations.” said Dumars about the Jennings theory before turning his attention to Boston. “I haven’t had any conversations with (Celtics GM) Danny Ainge about Brandon (Knight).” It was reported the Pistons had interest in a sign-and-trade with Jennings, a restricted free agent who’s a high volume, shoot-first and shoot-second point guard. He’s reportedly seeking a four-year deal that would place him among the highest paid point guards in the NBA, around $12 million annually. Bucks GM John Hammond worked under Dumars for a number of years, so a relationship is there but Dumars divulged their conversations centered on having similar pets, nothing more. “We were both talking about our dogs,” Dumars said. “That trade rumor is not true.” As for Rondo, Dumars can’t speak about his interest in any opposing player under contract publicly, as the Pistons would be hit with a six-figure tampering fine from the NBA, similar to the Houston Rockets getting fined before officially signing Dwight Howard. But the Pistons’ interest in Rondo makes more sense than Jennings, as Rondo is regarded as one of the best point guards in a point-guard heavy league. It was reported the Celtics would want Andre Drummond, which is a non-starter for the Pistons. “There are guys who, a pecking order of things we would or wouldn’t do, Drummond is certainly one of those guys we wouldn’t move,” said Dumars, who wouldn’t claim anyone else as “untouchable”. It doesn’t appear to mean the Pistons wouldn’t listen to phone calls on Greg Monroe, who’s one season away from entering restricted free agency, or even Knight, who’s entering his third season. “We’re still open to doing things,” Dumars said. “I’m not sure how much more. I feel good about where we are.” He insists he hasn’t dangled either of those players out in the open market. For Monroe, the Pistons would like to see how the Monroe-Drummond-Josh Smith front line works before doing anything drastic. But he made clear that he’d listen to reasonable trade inquiries. “I’m comfortable with this roster, really comfortable. But you can’t shut the door now,” Dumars said. “It’s the middle of July, it’s a long time before Oct. 1. If something comes up that can get us one step further, we’ll do it.”