If Zubrus wasn't injured or one of Josefson/Tedenby played better, Matteau would've been sent down after 5 games. He got lucky with the injuries and Devils lack of depth at wing so he had an extended stay.
Devils have been letting some of their prospects stay in the NHL for a lengthy look during the past few seasons with no real success. (Palmieri/Tedenby/Zharkov). Matteau happened to be that prospect this year and wasn't ready yet.
The weird thing is how everyone's situation is completely different. Zharkov had pretty much made the team as an energy guy under Lemaire, and then I guess Lou was expecting him to take some next step and he was demoted. Tedenby appeared to break out and then fell apart the next season. Palmieri never really broke out, but appeared good next to Kovalchuk. He was expected to take another step forward too and didn't impress.
I'm really hoping Josefson breaks the cycle, if only so that the Devils' streak of poor develop can come to a close. People are starting to cringe every time Lou drafts a Swede!