from Amazon
Wednesday, August 10, 2011
Stealing signs in Toronto?
ESPN reports:
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).
I’ve never looked, but let me take a really quick look here. And sign stealing would go beyond just batted balls. Walks, strikeouts, the whole thing comes into play. So, let’s see what we have:
In 2011, so far, Toronto batters’ OPS is 69 points higher at home. Their opponents are 47 points higher at Rogers. Since the typical home field advantage is about 30 or 40 points, seeing a 23 point advantage for Toronto batters over their opponents actually works against the theory, but in reality, it’s well within random chance.
How about 2010? Toronto batters had a 64 points advantage at home, while their opposing batters are 3 points under, giving a whopping 67 point differential (compared to the standard 30-40). Is that a big deal though? That’s about a 15 point wOBA advantage on 3000 PA. One standard deviation would be 9 points, so we’re talking under two SD. By itself, maybe there’s something to it. Maybe. But couple it with 2011, and there’s nothing there.
2009? The Toronto hitters were 8 points UNDER, while opposing hitters were 63 points UNDER. Quite a reversal of fortune for all concerned. Anyway, that’s a 57 point advantage for Toronto hitters. Putting the three years together, the 57, 67 and 23 points of advantage averages out to 52 OPS points, compared to the league average of 30 to 40 points. That’s about 7 wOBA points. Given 8000 PA, one SD is 5.7 wOBA points.
I don’t see it. And if you were to do all 30 teams, I’m sure you’ll find a couple of other teams with a bigger advantage at home than the Jays hitters.
If anything, the outlier is 2008, before all this apparently started. The Toronto hitters had a 28 point advantage at Rogers. But opposing hitters were 50 points UNDER, for a 78 point difference, far ahead of all subsequent seasons. In 2007, it was 37 point advantage for Toronto hitters, while opposing hitters were 47 points under, for an even greater 84 point differential. In 2006, Toronto hitters had a 100 point advantage, while opposing hitters were 48 points UNDER, for a super duper differential of 148 points! You want to talk about something weird, then go back to 2006. In 2005, it was 70 point advantage for Toronto hitters, while opposing hitters were 4 point UNDER, for a 74 point differential.
So, 2005-2008 is where Rogers was the huge advnantage for the hitters, averaging 96 points of OPS advantage (compared to presumably a 30-40 league average, though at this point, I’m too lazy to look that up). Anyway, that’s about a 25 wOBA difference on 12,000 PA. With one SD being 4.7 wOBA points, that’s 5 SD from the mean. That’s about as big an outlier as you’ll ever find.
If you want to investigate, go back to 2005-2008, and find out what happened at Rogers. 2009-2011? Nothing in comparison.
Thanks to B-R.com for the ease of data access.