The Bruins did Chiasson a bit of a favour by releasing him now. It gives him some time to find another team before the season officially gets underway. However, given the fact that he needed a PTO in the first place for training camp, another offer is likely a long-shot.
Chiasson was originally drafted by the Dallas Stars 38th overall in 2009, but didn't debut in the NHL for another two years. Other than Dallas, he's also suited up for Ottawa, Calgary, Washington, Edmonton, Vancouver, and Detroit. He has his name on the Stanley Cup from his season spent with the Capitals in 2017-18, and played in 16 post-season games that year.