Most of the book is about Walter's personal life. The Chapters that apply to sports betting are Master Class, Advanced Master Class, and War Stories. Those chapters cover only 47 pages.
I'm not a professional sports bettor so I'm not going to weigh in on the veracity of his system. I'm just commenting on what his methodology looks like to me.
And it looks to me that his system is 100% mathematical. Not half mathematical, not three quarters mathematical, not 95% mathematical....but 100% mathematical.
He starts out by saying everything comes down to value.
He bets according to power ratings. There are no hunches, opinions, gut feelings, none of that hoopla. His computer guys track every conceivable statistic and built models based on statistics going back to 1974.
His power ratings equate to the point spread. Best team in the league is around +10 and the worst team is about -10. A team that has a power rating of +7.5 is a 3.5 point favorite over a team with a +4.0 power rating. He compares his lines to the bookie lines and bets accordingly.
The raw power ratings are computer generated. Then adjustments are made for game factors. He has a mathematical value for every situation, weather condition and emotional factor.
For instance a warm team playing in 30 degree weather is docked .5 points from their power rating. If it's 20 degrees then a full point is deducted.
Quarterbacks are rated from 6 to 9.5. Mahomes is a 9.5 quarterback.
He says that injuries are the 2nd biggest factor after the raw power ratings. Every player in the league has a rating. Non QB players have a rating from 0.00 points to 3 points. If a player has a 2.0 power rating then gets injured then 2 points are deducted from the teams power rating. Then the power rating of the player that replaces him is added to the rating.
Everything is purely mathematical with him, except, he can't put a number on snow or heavy wind.