In regards to Matteau and the possibility of him sticking for the season... I want to bring up an NHL comparable who we've referred to when we've talked about his development; Lucic.
Looking at Lucic's stats, I'm seeing he played on the Bruins NHL squad right out of juniors. At age 19, having been drafted at #50.
Just wanted to mention that as food for thought, because if Matteau actually does stick for more than five games, it'll mean he's been consistently helping the team win, improving each game and that the coaching staff believes it's best for his development to play with the NHL club. (In my opinion anyways)
It's less rare than people think, prospects that young and drafted later making their case to stay with the big club when they get their chance. I'd be really excited to see Matteau stay with the Devils if his good play remains consistent and his development won't be stunted.