True, the Bruins dont have enough cap space right now. They're supposedly bringing back both Krejci and Bergeron as well so no doubt they're trying to move a contract. They've got $4.7M in space right now but also still need to sign Zacha who will take up at least $3.5M of that space.
Unless they end up doing something with Bergeron that's like $1M in base salary and up to $4-5M in performance bonuses or something of that sort.
On another note... Quickly browsing through all teams in the league, I count like 10 different teams in the league that are almost certainly trying to make a trade to move salary right now.
You've got Boston(For Bergeron), Toronto(Sandin), San Jose(Feraro and 3 RFA forwards, with just $2.2M in space right now), Vegas(Roy and Hague, but also only a 16 man roster as is and already $1.4M over the cap), Florida($3.3M over the cap), Islanders(Trying to sign Kadri but also have RFAs Dobson and Romanov to sign), Philly(100k over the cap with RFA Tippett and MacEwan still to sign), potentially Dallas($11.4M in cap space but have Robertson and Oettinger to sign still), Edmonton(under 100k in cap space right now. They do have a bit of LTIR room, but also a couple fairly significant RFAs to sign in Yamamoto and Puljujarvi). Colorado if we're going to sign Kadri will need to free up space. Carolina only has 19 players on its roster right now, just $4M in cap sapce and have Necas and Bear as RFAs, they need space. Pittsburgh is currently 500k(Though they can just run a 22 man roster and be fine).
Its going to be fascinating to see how some of these teams make it work. Never mind the fact you've also still got a number of good UFAs still in limbo as well. Kadri, Klingberg, Rodrigues, Heinen, and Stastny the biggest ones.
I honestly cant really see more then like 5 teams right now that actually have the cap space for Kadri or Klingberg. And two of them are Buffalo and Arizona