As reported by Elliotte Friedman, the Bruins were close to acquiring him and had a lot of interest in him, makes you think if that was going to be the return when Ullmark blocked a trade from sending him to the Kings.
Just one season after signing a 8-year $8.5 million contract with the Kings, there were rumours that he could be bought out, instead the Kings traded him and were able to get a decent return back.
Thankfully the Bruins didn't make a deal happen for PLD, for the type of player he is, this would have looked horrible on Don Sweeney.