In response to pumpsie-green's comment:
Teams win with good game callers. They can win much more, even if the other catcher is a way better hitter. Just because it can not be quantified with specific data, does not mean the catcher behind the plate doesn't have a large influence on how ell the pitcher does and hence how well the team does.
I agree. Some catchers, no doubt, call better games than others. I also agree that right now that ability cannot be quantified. You have produced a lot of data and facts about catchers and pitchers matching up. Again I ask you: are you a statistician? Do you know for a fact that what you have cited is statistically significant? Its interesting, for sure, but I do not know that it means much scientifically speaking. Can we call it "circumstancial evidence" for your case?
I was always pretty good at math even in college, but no, I am not a statistician.
I'd have to say that anyone with a half a brain who looks at all the evidence and results from hundreds of sample sizes from individual pitchers over several seasons (1 by 1), and realize that even though the individual sample sizes are small, that over a long time frame, the large sample size of the small sample sizes indicate a clear trend is noticable.
Here's an example:
Let's say we flip a coin in small sample sizes like just 4 times, but we repeat those small sample sizes 1000 times. We'd expect the results to come out pretty even, right? Like maybe:
375 times: 2H/2T
250 times: 3H/1T
250 times: 1H/3T
63 times: 4H/0T
62 times: 0H/4T
I'd say that if we had 1000 small sample sizes of pitchers with VTek vs pitchers with other catchers and found that the expected outcome should be about:
400 times very close ERAs
300 times a better CERA with VTek
300 times a better CERA with the other catcher
but, instead we found:
300 times with a very close CERA
600 times with a better CERA with Vtek
100 times with a better CERA with the other catcher,
one could say there is an influence working on the numbers in Vtek's favor.
We can not say it is because Vtek catches better pitchers, because that is taken out of the equation by counting each pitcher's individual numbers as an equal result one by one. Vtek caught a pitcher more in a good year than someone else in a bad year? Nope, we are taking each season one by one. One catcher has a worse defense behind him? Not likely, since for the most part each pitcher is pitching with the same team behind him night in and night out, but yes some variables are influential to some (small) degree. Strength of opponents? Again, some variables must be involved, but over long periods of time, one might expect them to even out or at least not be highly significant.
I do not take CERA at face value. I know there are outside influences on the numbers just like there is for BA, OBP, ERA, WHIP and any stat. I have never compared Vtek's CERA to a catcher on another team, or to a catcher on the same team but from a different season. To me, this severely restricts the useage of CERA and OPS against, but none the less, it does tell us one thing pretty clearly: some teams have one catcher that pitchers do much better with than the other one. Some teams have equal or close to equal catcher tandems. Some catchers have poor records with the staff they are catching, regardless of what team they are on (See Napoli with Texas and Toronto: he only has had one season where he did better than his co-catcher. See VMart with Cleveland before coming to Boston.) Some catchers have good records with their staff, regardless of what team they are on (see Mathis on Toronto last year).
I've seeen enough numbers to be pretty darn certain that other variables are causing the differentials. I've also heard countless catchers praise Vtek for his game-calling skills, his hard work and dedication to studying the game and batter tendancies, perhaps like no other catcher in baseball history has done. It worked. It made a difference. i am sure of it, even if I am but an math amateur.
When Vtek was showing a full run better CERA than VMart, I never claimed he was a full run better, but I would be pretty certain that he might have made a half a run difference on average at worst. The team record with Vtek, even if you take away the Beckett games, show the pattern continued.
VTek had a poor throwing record, one of the most over-used defensive catcher stat know to baseball, and yet teams scored less when he was the catcher. It didn't matter who was pitching, the results were nearly all the same. year after year after year. It doesn't take a rocket scientist to accept that Vtek was influencing the results, even if in some unkown way. I don't need to know the exact reason of the influence: it could be voodoo for all I care, but to me the facts are undeniable. VTek made a huge difference to the pitchers he caught, and they will all tell you the same thing. That's enough for me.