A healthy Jordan Staal would be a fantastic cog on any team. Not sure why that is a negative.
What type of measurement would be more satisfying for you to use than 2 months? He is in his rookie year so its not like we have a wealth of game experience to go back on and review at the NHL level. He has been getting progressively better as the year has gone on, as you would hope with a rookie, and is shooting his way up the Canucks depth chart. Are you honestly trying to argue that a rookie who doesn't instantly start playing to their potential from game 1 is handicapped in the future by that in some way?
He has been a player that has been progressing at an incredible rate over the course of the season, and any discussions that we have around him should be based on the player he is now, rather than some irrelevant full season average figure. To me it just seems obvious that all people are doing is pulling up his stats from the entire year, and assuming they know everything there is to know about how Horvat has played this year.