Comments on Winn's new power and batting 3rd I posted on blog elsewhere
The only reason they are thinking of him in the power position is his unusual spurt of power once traded to the Giants. He has averaged 20 AB/HR at SBC, 17 AB/HR overall, since joining the Giants.
Reasons why he's been hitting better and for more power? Maybe being able to go to his home in nearby Danville and seeing his wife and getting home cooking has really relaxed him and released his potential. Perhaps newness in the league but I would have to assume that this would quickly be figured out. I thought this when he started out hot but then cooled off. Then he suddenly got even hotter.
Sabean thought that Winn was more suited for the NL-style of pitching (see article). Winn himself said that he hasn't noticed more fastballs in the NL but that pitchers are more aggressive due to their need to keep their pitch count low, in order to stay in the game. Thus, even if they throw an offspeed pitch early in the count, it is usually a strike. And being an aggressive hitter himself, that has played into his way of hitting.
It also helped, him moving away from SAFECO, as he had a career 48 AB/HR there, but an OK .284/.364/.395/.759 hitting line despite the lack of homers, I guess he made up for it with doubles and triples that didn't become homers.
Not as scientific but certainly fanatical :^) I went to the Giants website and pulled up Winn's hit chart, which shows the location of each of the balls he hit and the result, whether hit or out, at each ballpark. Each field looked like they are scaled the same so I pulled up his hit charts for SBC, SAFECO and Tropicana, his three home parks (for some reason they don't allow an option to see all the hits where they landed with a fenceless field), printed them out, and eyeballed them aligning the diamonds together.
From that admittedly unrobust analysis, I would say that the move from Tropicana and Safeco to SBC would roughly double Winn's homer totals at home.