Playing Matta for 22+ minutes a night sounds like a bad plan. If the kings expect to improve next season with Matta in the lineup, he would slot in as a second pair defender playing 18 minutes a game. From all accounts, his skating isn’t good enough to play on the top D pair.
In the absence of additional moves, we’re looking at Bjornfot or Anderson playing with Doughty. Personally, I would love to see that type of experiment take place next season. Give the kids a real shot on the NHL roster and turn your #1 LHD into a platoon situation. You can give them both PP time and save their legs for even strength minutes by sheltering them from the main two PK pairs.
By the quarter season point you should have a good read on both players. And you can make a deal if one isn’t working out.