No, I have issues with it, but its the best we got.
Check out the link above.
In, 2007, Fenway had an offensive PF of 1.17
In, 2006, Fenway had an offensive PF of 1.03
In, 2005, Fenway had an offensive PF of 1.03
In, 2004, Fenway had an offensive PF of 1.12

Did they move the fences at Fenway? No.
Run scoring by different teams against different pitchers in different parks is just somewhat random.
The good news is these ‘+’ stats measure players relative to one another in any one (same) given year.
But I don’t think they are not really relative to the same player across different years.

Here is how the ESPN defined it for offensive stats:

A rate higher than 1.000 favors the hitter. Below 1.000 favors the pitcher.

PF = ((homeRS + homeRA)/(homeG)) / ((roadRS + roadRA)/(roadG))

I’m GUESSING that for pitchers Park Factors, they use EARNED RS, but I don’t know for sure.

For example: Lets say the Yanks play the Mets all 162 games.
Over the 162 games, in the 81 played at Yankee stadium, there are 1000 earned runs scored.
Over the 162 games, in the 81 played at Shea stadium, there are 800 earned runs scored.

So, if the same 2 teams score 1000 at Yankee but only 800 at Shea, Shea is a ‘pitchers’ park, and Yankee Stadium is not. So the Pitchers for the Mets have an advantage when compared to the Pitcher at Yankee Stadium.

So the Shea Park Factor for pitching is 800/1000 = 0.8
So the Yankee Park Factor for pitching is 1000/800 = 1.25
If a Shea pitcher has an ERA of 4.0 at HOME and
If a Shea pitcher has an ERA of 4.0 at AWAY
His HOME games ERA+ is calculated as: 4.0/0.8 = 5.0
His AWAY games ERA+ is the same as his ERA: 4.00
So his total ERA+ (Home and Away) = (4.0 + 5.0)/2 = 4.5

If a Yankee pitcher has an ERA of 4.0 at HOME and
If a Yankee pitcher has an ERA of 4.0 at AWAY
His HOME games ERA+ is calculated as: 4.0/1.25 = 3.2
His AWAY games ERA+ is the same as his ERA: 4.00
So his total ERA+ (Home and Away) = (4.0 + 3.2)/2 = 3.6

So… both pitchers have and ERA (not adjusted) of 4.0
Because it’s easier to score runs at Yankee (and therefore a disadvantage for the pitcher) is ERA+ is 3.6
Because it’s harder to score runs at Shea (and therefore ad advantage for the pitcher) is ERA+ is 4.5

HOWEVER, if NEXT year, by coincidence, the those teams score
800 and Yankee and 1000 at Shea, for that year, the Park Factors would be reversed of the first case.

So it is NOT scientific, but based SOLELY on the ACTUAL RUNS scored in that year, by each park.

it does not account for defense. you’d have to dig deeper for other pitching stats to try to tease out the effect of defense.

I’d be curious to hear how the adjusted ERA stat quantifies differences in sizes and layouts of a pitcher’s ballpark, talent and peformance disparities in AL v. NL, and the quality of the defense behind him.

yes, i would do that trade in a heartbeat, and so would the Yankees. i think the Yankees would do McCutchen for Blanton as well.

but i don’t think the A’s would.

the A’s would be looking for guys like Tabata, Jackson, Betances, etc.

then it gets cloudier.

i agree, Blanton would help the Yankees in 2008. but i don’t know if i’d start giving up 2-3 top prospects for him.

ERA + (or adjusted ERA) is a useful stat, especially for pitchers who pitch in parks that tend to favor pitching or hitting to an extreme.

It basically “normalizes” a pitchers ERA. Basically is compares one pitchers ERA’s to other pitchers ERA’s and adjusts for ball park and league related factors.

Here’s a definition from the hard ball times:

ERA+
ERA measured against the league average, and adjusted for ballpark factors. An ERA+ over 100 is better than average, less than 100 is below average.

So in Blanton’s case I think this statistic tells you a lot becuae of McAffee park and how it helps pitching. His ERA+ last year was 106. That’s just a hair above average. The year below his ERA+ was 92 – a hair below average.

Blanton is a league average pitcher. Almost to a T. Sure he eats innings but while he’s eating those innings he’s only going to give you an average performance.

Given the scarcity of pitching that’s not bad. Especially if you are team like the Reds and you’re desperate for a starter.

But its hardly worth what Beane is asking.

Fortunately, the yankees may be through with the day where they had to make bad moves out of desperation for average pitchers like blanton.