Well that is because you are a wings fan, not a hockey fan. Hockey fans can actually enjoy watching many different teams and leagues and follow players from juniors up,, making it irrelevant how good their favorite team is. Furthermore, even if I accepted your premise, could it not be argued that someone who's team has had bust after bust are better able to point out red flags in a player's development better than you?
Wrong. I am hockey fan first. Detroit is just my favorite NHL team now.
You're right, though, that seeing bust after bust you would expect someone is able to know better what things young players do that would prevent them from being successful NHLers.
The premise is based off fans who primarily follow 1 team, which the majority of people do. For example, casual Chicago fans thought that Duncan Keith's career would be as good as Nick Lidstrom, which casual Detroit fans knew wouldn't be the case. This is on average, and not the case 100%, but usually. Obviously there is a ton of homerism involved in this specific example.
A casual Detroit fan, after watching Lidstrom, McCrimmon, Howe, Coffey, Konstantinov, Fetisov, Murphy, Chelios, Rafalski, etc, is more likely to notice (in my experience dealing/discussing with thousands of fans) what younger players' habits translates to the NHL than an Oilers fan of the same generation. On the flip side, that EDM fan may notice more warts. The difference being total potential. Teams develop the good in players and tend to focus on upside. They can usually tell where the person needs development or discover it naturally.
Regardless, my comments aren't rules, just experiences about casual fans that I think some people took too literally or black and white. It's not.
Back to the topic, which is the player, would Habs fans be happy if his production "stales" at center this year in Liiga? If he stayed on wing I would expect/hope his numbers to rise, but "switching" to center may not flatter his point totals. If he plays center all year and his numbers rise then that would be good for both player and team.