In his defense, Grabovski is a Jan 31 birthday, making him as young as possible and still qualify as 23/24 in his NHL seasons on hockey-referece. Why are so many Habs clustered right around Feb 1? It's a nuisance. Nevertheless, he's still older than the players he's competing with for icetime.
At 23/24, tiny Oleg Petrov was dominant in the AHL but not quite good enough to permanently crack a pretty good lineup in Montreal. In his second stint he was in his prime (28 to 31) and made a bad team slightly better.
The story appears to be the same for Grabovski. He's not going to crack the lineup of a contender. Most pundits say he's bound for a European league next season. It sucks to lose a good depth player but that's the way the league works these days.