Does that mean winning the Brownlow is bad for your team in the GF?
Well, the new Brownlow Medalist has played in that year Grand Final 24 times over the years, and in recent history, its happened 8 times in the past 11 years.
In fact since Robert Harvey won in 98 and didnt play in the Grand Final, only Shane Crawford in 1999, Goodes and Ricciuto in 2003, and Chris Judd in 2004 haven't made the Grand Final.
I would say that this points to Chad and Kane Cornes, Jimmy Bartel and Gary Ablett and to a lesser degree Dom Cassisi and Joel Corey, being in the box seats in regard to winning the Medal.
In regard to your question Lippo, I would having a player win a Brownlow is good indication that your team is in good shape; since 1996, every Brownlow Medalist has played in the finals bar Crawford (Hawthorn finished 9th and only 1/2 a game out of 8th spot).
However in regard to the Brownlow Medalist's team winning the Premiership, all the recent losers of Grand Finals (2000 onwards) have had these things against them:
Both Melbourne (2000) and Collingwood (2003) were considered massive underdogs, and on the day both Woewodin (with 19 touches) and Buckley (24 disposals and the Norm Smith Medal) played well.
In 2005 and 2006, you could almost say that the team that lost (2005-WCE, 2006-Sydney) could have easily won, and Judd was the Norm Smith Medalist and while Goodes supposedly stuffed up at the end of the game, he was also great.
In closing, I would have to say that it depend on the player; Kane and Chad Cornes have been to the big day before (with Kane Cornes being among the best and unlucky to not get the Norm Smith Medal) and Bartel and Ablett were, with Ottens, the Cats best on friday night in a massive game, so I honestly would say it wont affect those players unless it they let it.