The Dallas Stars recently posted a good explanation of this process, excerpted below:
Mike Fornabaio notes the Isles did not qualify McNeely, Romano, Riendeau (obtained in the Rolston trade) and Alexandrov (obtained from Boston in late March for futures). None of these players ever appeared in a game for the Isles. The non-qualifiers will become unrestricted FAs on Sunday.
Also not qualified today: Blake Comeau (per James Mirtle). The Flames would have had to offer a $2.5 million QO to keep Comeau, who went 5-10-15 in 58 games for Calgary, after starting the season pointless in 16 games for the Isles. Comeau is still only 26, so I'm sure he'll get another chance somewhere, albeit at a significant pay cut.