Fine, because Berggren "graduating" doesn't really mean anything other than you personally don't list him in the prospect pool. But either way he's a 22 year old who is in his rookie season.
The prospect pool discussion is hollow because of arbitrary qualifications that are placed on it. Like Raymond isn't considered a prospect at ages 20, but Soderblom is, despite being older than Raymond. And Johansson is a prospect, but Seider isn't, even though Johansson is older. Just because a player is good, doesn't mean that they are less prospect, just that they are a better prospect. To me, considering someone is graduated means you consider most of their development curve completed.
Like I could say that the Sabres prospect pool is weak because it is led by only Matt Savoie. Pretending that they don't also have Owen Power, Jack Quinn, JJ Peterka, Dylan Cozens, Mattias Samuelsson, Peyton Krebs and Rasmus Dahlin at 22 and under. What do they really have to be concerned about? So is their prospect pool bad, or are they stacked to the brim in really young, high end NHL talent. Or can prospect pool and NHL roster have some overlap?