I just read and reread the first "Decision tree" article in contrarian's "celebrating the Best of the SLB Forum" I am not as experienced as so many of you are and I have not been able to find and watch Paul Bessire's PowerPoint demo, so if I am missing something here, please inform me, but I do not agree with some of the logic flowing from the thread, especially that 1B in park effects is the sole determiner of whether a ballpark turns a hit into an out or an out into a hit. I have a theory that seems to fit better with the evidence.
The consensus in the forum is amply demonstrated by this comment from one of the, admittedly, most knowledgeable members of the WIS forum. He says:
"In reviewing the Powerpoint slides from that presentation, it appears Step 4 uses the 1B factor to help determine Hit or Out, and that's the only time it's used. Steps 7 and 9 then use the HR, 2B, and 3B factors to determine if the hit is one of those types. Everything not determined to be a 2B, 3B, or HR then by default is just a single. That's how it appears to me anyway. The Powerpoint actually says the "hits multiplier" is used in what is Step 4 above, which could only be the 1B factor because the 1B factor is not mentioned anywhere else in the slides."
From this we learn A) Step 4, which determines hit or out, is affected by the "hits multiplier" in the stadium stats; B) The 1B factor is not mentioned in Bessire's presentation; C) That 1B in park effects is the same as "hits multiplier" is a logical conclusion based on insufficient clarity in the Powerpoint presentation. It is a logical conclusion, but i do not think it is entirely correct for the following reasons. First, why call it the "hits multiplier" if it is called the 1B park effect in WIS? Second, why should the 1B do a different task than the 2B, 3B, and HR? If 1B determined hits, it should be called hits, not 1B.
My suspicion is that 1B really does what the name says: reveals the likelihood that a hit will be a single. If so, then the question remains, what is the "hits multiplier"? I would suggest the hits multiplier is none other than the park factor. The player's BA, after other factors (pitcher, defense, etc) are weighed in, is multiplied by the park factor to change the percentage of ABs that become hits.
For example, a player with 600 ABs with a BA of .300 will have 180 hits. If 1,000 balls are thrown into the bucket, there will be 300 balls with "hit" written on it. The other 700 will be outs. But at Coors, where the park factor is 1.37, that number jumps to .411. In Petco, with a park factor of 0.82, the number falls to .246. So a .300 hitter at a neutral park will hit .411 in Coors and .246 at Petco. Of course, players do not play in neutral parks, normalization affects things, as well as numerous other factors. But this seems realistic to me.
As for why 1B is not mentioned in the Powerpoint demo, I think the post I quoted contained the answer. The decision tree asks if the hit was a HR, then a 3B, then a 2B. If it was none of these, it defaults into a 1B. Since 1B is a default category, it need not be mentioned in the explanation.
Please let me know if htis sounds like a plausible explanation for how park effects and park factor relate to the decision tree. I am determined to learn how to use the stadiums in WIS, and knowing the answer to this mystery will help a lot.