By Tobias J. Moskowitz and L. Jon Wertheim

Hidden influences on how sports are played and won

Whistle Swallowing

  • All about officials and omission bias with loss aversion

  • Uses Mike Carey and David Tyree catch as fundamental example.

Acts of Omission

  • The absence of an act - as far less harmful than acts of commission - actually committing the act, even if the outcomes are the same or worse

  • Food example - declining healthy food is a poor choice (omission), but eating junk food is worse (commission)

Omission or Comission

  • Jeff Bezos quote - “people overfocus on errors of commission, failure’s not that expensive, the big cost you incur is harder to notice, errors of omission.”

  • Officials or refs, when the game steps up, you step down

Subjective calls

  • Swallow the whistle with judgement calls versus subjective calls when the game is about to end

  • Subjective in football - holding, illegal blocks, illegal contact, and unnecessary roughness don’t happen as often when game is on the line or at its end

  • Objective calls - delay of game, illegal formation, motion, or shift are called at the same rate

Go for it

  • Kevin Kelley always going for it on 4th down and never punting

  • He plays the odds and he also has job security and freedom to do so

  • All about risk aversion

Losing hurts

  • Sparky Anderson - losing hurts twice as bad as winning feels good.

  • Would you rather want a $5 discount or avoid a $5 surcharge?

Why take risks

  • You’re more likely to risk something when you expect to lose

  • Job security is huge. Are you allowed to fail or be unconventional?

  • Belichick was not as aggressive until he won a Super Bowl. It built equity for him to take risks, fail, and not lose his job

LaRussa example

  • Players must buy in too.

  • Tony LaRussa tried using pitchers for 3 innings apiece, but players didn’t like it. They wanted wins (throw for 5 innings), because it drives their contracts

Westhead example

  • Paul Westhead’s playing style at Lakers, didn’t work

  • It worked at Loyola Marymount, but failed spectacularly with Denver Nuggets

  • Players buy in matters.

Tiger Woods is human

  • More about loss aversion, it’s a principle we dislike losing a dollar more than we enjoy earning a dollar

  • PGA tour, measured putts from identical distance for birdies and pars, putts for par were far more successful

  • Players were so concerned with a loss, you’re more aggressive in avoiding bogey than scoring birdie

Birdie putts

  • Tendency to leave putts short for birdie, being too conservative.

  • Woods even says the psychological difference between making a birdie and dropping a shot is huge, more important to make a par putt. He’s human

Gain and loss

  • In the face of gain, we’re conservative

  • In the face of loss, we’re aggressive.

  • It’s hard to block out how you got in a predicament. Remain even keel

Endowment effect

  • Feel the loss of something you own much more deeply than the loss of something you don’t own

  • When you own, you’re invested emotionally in a thing versus not tied to it

Offense wins Championships

  • Defense is no more important than offense, both are equally important

  • Defense requires effort, it’s less glorified, harder to measure, and dark (hidden)

Value of a blocked shot

  • The value of blocked shots is in the details.

  • Blocked shot back to opponent was assigned a value

  • Blocked shot out of bounds was slightly more valuable

  • Blocked ball to a teammate was worth the most

Value of the act

  • It’s the value of the act, not the act itself that matters

  • Counting is easy, measuring value is hard

  • Tim Duncan’s 149 blocks were more valuable than Dwight Howard’s 232 blocks

Rounding first

  • People have a bias to round numbers

  • It’s why more batters hit .300 than .299.

  • A batter is close to .300 at end of season? He won’t play.

Incentive bias

  • A rounder number (100 RBI, .300) usually leads to better salary

  • Bobby Abreu finished with exactly 20 or 30 home runs five times, seven times exactly 100 or 100 RBI, and no seasons with 95 to 99 RBI

  • Same true in NFL with 1,000 rushers

Where to find value?

  • You can find value in looking at players just below these round number benchmarks

  • Just below .300 or below 1,000 rushers

Rooney Rule

  • The drop-off of African American coaches winning is actually a good thing

  • Why? It validates the Rooney rule

  • Black coaches are held to same standard as white counterparts. They’re equal

Comforts of Home

  • There is a home-field advantage in all sports

  • It’s a bit more strong in some sports, but it’s the same regardless of where sport is played

  • There is significant incentive to win at home - concessions, people leave happy, spend more money

Why does home field advantage exist?

  • Because of crowd support? No. Look at kicks in football, free throws, shootouts - when you control for a situation where crowd could impact game, it really doesn’t

  • Because of travel? No, evidence isn’t strong that travel plays a major role.

  • Because of scheduling? Yes.


  • NBA teams play lots of back-to-back games, and this does favor the home team

  • It’s less of an issue in certain sports like MLB

  • More extreme in college football. Teams pad schedule with hosting weak opponents

Home field advantages

  • Scheduling bias explains some of home field advantage, but not in baseball or NFL or soccer at all

  • Because of unique home characteristics? Not really, some impact, but not huge difference. Hard to really have an edge with unique home fields today

Officials drive home advantage

  • Officials or referee bias is most significant factor

  • Study used QuesTec data to determine officials or umpires side with the home team in pressure situations on borderline calls

  • More ambiguous the call? More likely to go in home team’s favor.

Officials have confirmation bias

  • Humans conform because they want to fit in and because they believe the group is better informed than they are

  • Officials aren’t really aware of the bias, it’s just a natural human response

?s on home field advantage

    1. Why does home field advantage differ across sports?
  • Because refs or officials are more important or have more influence on the game. Soccer more than baseball. A penalty kick is huge, where umpire calls are fairly black and white.

More ?s on home field advantage

    1. Why is it the same for a sport no matter where its played?
  • Because the role of the referee is the same no matter if soccer is played in America or Europe or Spain.

More ?s on home field advantage

    1. Why hasn’t it changed much over time?
  • Because the officials role hasn’t changed with the rules.

No I in team

  • But there is an m and an e

  • There is a bigger influence of superstars in certain sports like basketball

  • Disagree with soccer, think it’s much less

  • Makes sense in basketball. Only 5 players play at a time

Michael Jordan

  • Where in baseball, a player might only get 3 at-bats a game

  • In soccer, only a few touches by your best attacker.

  • Michael Jordan - There is an I in win. So which way do you want it?

NFL Trades

  • Off the chart Mike McCoy came to own the NFL draft using a value chart that was largely designed off assumptions.

  • Tried to answer - what is the value of a draft pick in a certain round?

  • Value of the first pick in draft was 3000, and first pick in second round 580, and final pick was 0.4

Chart gave value

  • The chart just gave the Cowboys a framework

  • It more or less stated value in multiple picks versus one high pick

  • Opposite is when the Saints traded eight draft picks for Ricky Williams. Overpaid by a ton

Why did it become obsolete?

  • Eventually when all teams started using the chart, it became obsolete

  • Thaler and Massey found inefficiencies

  • Teams would overpay to pick today versus playing the long game. Not comfortable with uncertainty

Evaluating Talent

  • It takes talent to evaluate talent.

  • Draft pick value is different for different sports. Seven rounds in NFL, just two in NBA, and 50 in MLB

  • Find value by looking at the details. Ask why

  • Brady didn’t play at Michigan more because of political reasons than his ability

Rule Changes

  • Coin toss trumps all: If you won the coin toss in overtime for NFL, you win 61 percent of time

  • This prompted changes in the NFL overtime rule. It wasn’t really fair

Mitchell Report

  • What isn’t in the Mitchell Report Dominican players were more likely to take steroids because of cultural and situational needs

  • All incentive bias

  • The upside was far greater for Dominican players than American players. A lot of Dominicans were much younger, where American players were older and trying to get one last big contract

Does icing the kicker or shooter work?

  • No. It’s a lukewarm strategy.

  • Study looked at NFL kicks and NBA free throws. Found no difference in performance

Myth of the hot hand

  • Momentum in sports doesn’t exist. We just believe it does because we like patterns

  • We don’t like mystery.

  • Randomness and luck resist explanation


  • Try flipping a coin 100 times. There will be streaks of heads or tails

  • Those streaks don’t increase the odds the next flip will land on heads.

  • We do a really poor job at understanding randomness. You aren’t due for anything. Your chances do not change because of a streak.

Sample sizes and Randomness

  • The true quality of teams can be measured in large sample sizes

  • Small samples are dominated by randomness


  • You can make numbers say whatever you want. It’s selective. And more than one thing can be true

  • Be objective. Neutral. Look at as much data as possible to get a more accurate picture

  • Not just short-term numbers

Cubs cursed?

  • No, they’re not cursed or super unlucky.

  • It was deeply ingrained in the team that wins and losses didn’t matter

  • Wrigley wanted fans to enjoy the ballgame, win or lose. Lovable losers

Cubs curse continued

  • Cubs could lose and attendance could go up. This wasn’t the case for almost all other teams.

  • Beer prices remained flat. Cubs fans went to game for experience, not for wins.

  • Curses aren’t to blame or Steve Bartman.

Purpose of the book

  • Ignore data and diverse views as your own peril

  • Seek controversial or opposite opinions and challenge convention to improve your decision making

The End

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