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2021 NFL Week 4: Capping with Pythagoras

Taking points with a couple of home dogs: Patriots +7 & Vikings +2


The Tampa Bay Buccaneers are slated as 7-point favorites in Tom Brady's first return to New England since the G.O.A.T. blew out of Foxborough. The meeting will come after the Bucs were dealt their first loss of the young season at the Rams last week. Coach Bill Belichick's new-look Patriots will try to stifle Brady's desire to right-foot the Bucs' cause off surprise losses in weeks 1 and 3.


In other action, Cleveland lost (but covered) at Kansas City to kick off their season, but enjoyed two comfortable wins more recently. The Browns are listed as slight favorites at Minnesota in week 4, after embarrassing the visiting Bears by a 20- point margin last week. The Vikings bested the Seahawks in week 3, but were surprised at the Bengals to kick off the season, and came up just short at the Cardinals a week later.


We have observed that the from the present situation, the betting public tends to extrapolate poorer teams' struggles into the indefinite future. This phenomenon commonly manifests in betting markets as herding around darling favorites, and has proven especially costly early in the season (a period when the best players are more likely to exhibit inactivity-related rust).


Consistent with this line of thinking, at present 87% of ATS bets on Bucs / Patriots tracked by SportsInsights.com are down on the Lombardi trophy-hoisting Buccaneers, while at 85%, dollars wagered are similarly skewed Tampa Bay's way. Similarly, 61% of ATS bets and 69% of spread dollars committed to Browns / Vikings are with Cleveland -- representing a smaller, but still rather extreme, tilt. The system described below seeks to exploit this recency bias and has delivered an 18% return on investment since 2005, including a 5-2 ATS run so far this year.


Over the first quarter of the regular NFL season, back non-conference dogs with win rates below their Pythagorean Expectation to cover the spread...



The Pythagorean Expectation is a simple method of forecasting expected win rates. It's only inputs are points allowed and points scored. Bill James reportedly developed the approach for baseball, but it has been co-opted for NFL use by the Football Outsiders. Data suggests Pythagorean Expectation is a superior forecasting tool to actual record. While, the angle detailed above incorporates this statistic to generate statistically significant long-term profit.

(In addition to blessing the Pats and Vikings versus the spread, this system also endorses the Eagles versus the Chiefs and Steelers at Green Bay for week 4.)


Note: Despite the title of this piece, Pythagoras of Samos, the Greek philosopher, contributed nothing to this finding. It is alleged that Pythagorean Expectation is so named simply because it resembles the Pythagorean Theorem (which might be useful for trying to ascertain lengths of legs of right triangles, but not much else).


In addition to the contextual support laid out above, our power rankings composite framework too endorses plays on Vikings' and Patriots' covers Sunday. The exhibit below indicates each game on the NFL week 4 docket for which our power rankings approach generates a definitive pick (the "Composite" column indicates our fair value estimate of the home spread; "Wagers" and "Vigorish" represent lines listed at Bovada.lv as of the time of this writing).



Per the table, we make the Vikings ever-so-slight favorites Sunday, implying close to a field goal's worth value with the home dogs in Minnesota. Additionally, we have the Browns as less than three points better than the Pats, likewise hinting at ample value taking the chalk with the home team.


Happy betting!!


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