Several Jays had extreme splits in 2010. Bautista, for example, had a 1.118 OPS (on-base plus slugging) with 33 homers at home but an .879 OPS and 21 dingers on the road. First baseman Adam Lind had a .759 OPS with 15 homers in Toronto but a .660 OPS with eight bombs on the road. Second baseman Aaron Hill? His home-road OPS split was .730-.605. Shortstop Yunel Escobar was traded from Atlanta to Toronto in July 2010, and he has an .865 OPS at Rogers as a Jay but a .683 mark on the road. And then there's Vernon Wells. The outfielder had a .990 OPS and 21 home runs in Toronto last season but crashed to .699 with 10 jacks away from Rogers Centre. This past winter he was traded to the Angels and has a .552 OPS in Halos home games.
Now, by themselves, the above splits aren't conclusive, so to measure the effect of Rogers Centre more precisely, The Mag consulted with Wyers. He has developed a method that generates park factors by comparing a player's performance in any given park with his performance in all other parks, not just in road games for that player. This reduces statistical noise and offers a better estimate of how a park actually plays in a given season. Wyers found that for every ball that batters made contact with in 2010, Rogers added .011 home runs, up from a rate of just .002 from 2005 to 2009. That puts Rogers Centre in 2010 among the top 3 percent of home run ballparks since 1950.
But only the Blue Jays, and not their opponents, got a home run boost in Toronto. When the Jays were on the road in 2010, they hit home runs in 4 percent of plate appearances in which they made contact, compared with an AL average of 3.6 percent. At Rogers, their home run on contact rate soared to 5.4 percent, which is a home-field advantage seven times the magnitude teams typically enjoy.
Opposing batters, however, actually homered on contact at a below-average rate in Toronto. As a result, the power differential between home and visiting hitters at Rogers in 2010 was the third largest of any park in any season over the past 60 years (see chart).
Just a summary for people who couldn't bother to read. Wyers isn't looking to grind an axe, he's just merely pointing out what the numbers indicate.
Vernon Wells is clearly the most damning piece of circumstantial evidence there is though.