When you're in school, report cards are rigid documents that chronicle your success or failure.
(Unless of course you attempt to manually change a grade so you don't get your video game console taken away by angry parents, which may or may not be applicable to your humble author.)
But in the NHL, report cards are a bit more malleable thanks to the benefit of hindsight. A "bad" signing in July can suddenly look better several months later. A "good" trade in June can be seen as abjectly terrible by the All-Star break.
As the 2017-18 season crosses the halfway mark, we're getting a better sense of which offseason moves worked and which ones flopped hard, so we've decided to re-grade NHL teams.