Saturday, November 30, 2013

Michigan Plays for the Win

Michigan nearly pulled off an upset with huge BCS implications this afternoon, falling just short against the Buckeyes. The Wolverines had scored a touchdown with 30 seconds to go in regulation, and could have tied the game with an extra point. Michigan instead chose to play for the win by going for two. According to a Michigan tweet:
Taylor Lewan, on the two point attempt, "Coach Hoke asked us seniors, do you want to go for it, we all said yes."
And though the two point conversion attempt failed, their seniors still made the right call. Michigan was a 15.5 point underdog at home against Ohio State. As I pointed out in last week's post, underdogs fare poorly in overtime. There have been 92 college football games in which a 10 point or more underdog has gone to overtime. They have won just 35% of those contests. The results are consistent across other sports.

I believe 2 point conversion attempts succeed a little less than 50% of the time (I could not track down hard numbers on this for college football). So let's say that the chance of success is 45%. Here is Michigan's win probability* for both strategies:

  • Go For 2: 45%
  • Play for Overtime: 35%

And the 35% is probably a bit high since it includes underdogs of 10 points or more. For underdogs greater than 15 points, those teams have won 32% of overtime games. So, unless Coach Hoke thought his team had less than a ~33% chance of making that two point conversion, going for two was the smart call.

* Note that I am ignoring the possibility of the Buckeyes driving for a quick score in the last 30 seconds of regulation. But even if that had a 10% likelihood (which seems high), that would take the 45% down to 40%, which is still better than 35%. And that assumes that they would not try to score if the game was tied.

Wednesday, November 27, 2013

Playoff Implications - Week 13

Here is your weekly cheat sheet for NFL games with playoff implications. The purpose of this feature is to highlight games that have a big impact on the playoff picture (see this post for background).

Ranking Week 13 Games by Leverage

The table below ranks the week 13 games by total leverage. Leverage in this context is a measure of both how uncertain a game's outcome is (games between evenly matched teams have higher leverage) and how much the playoff picture swings as a result of that outcome.

Turnover Index - Week 13

Here are the Turnover Index picks for Week 13. The Turnover Index is a simple betting strategy based on the theory that the market overvalues defensive turnovers when judging team strength. See here and here for more background.

Week 12 results

The Week 12 pick went 1-0 against the spread, with a $34 gain to the bankroll. Here are the season to date results:
  • Against the Spread: 9-13-1
  • Starting Bankroll: $1,000
  • Current Bankroll: $775 (-22% ROI)
Here is the week by week performance:

weekbetswonstarting
bankroll
amount betprofitsending
bankroll
4 2 0 $1,000 $268 (26.8%) ($268) $731
6 1 1 $731 $32 (4.5%) $29 $761
7 3 3 $761 $130 (17.1%) $118 $879
8 3 1 $879 $70 (8.1%) ($12) $867
9 7 2 $867 $166 (19.2%) ($66) $800
10 4 1.5 $800 $95 (11.9%) ($45) $755
11 2 0 $755 $14 (1.9%) ($14) $741
12 1 1 $741 $37 (5.1%) $34 $775

Saturday, November 23, 2013

Playoff Implications - Week 12

Here is your weekly cheat sheet for NFL games with playoff implications. The purpose of this feature is to highlight games that have a big impact on the playoff picture (see this post for background).

Ranking Week 12 Games by Leverage

The table below ranks the week 12 games by total leverage. Leverage in this context is a measure of both how uncertain a game's outcome is (games between evenly matched teams have higher leverage) and how much the playoff picture swings as a result of that outcome.

Wednesday, November 20, 2013

Turnover Index - Week 12

Here are the Turnover Index picks for Week 12. The Turnover Index is a simple betting strategy based on the theory that the market overvalues defensive turnovers when judging team strength. See here and here for more background.

Week 11 results

It's been a rough four weeks. Week 11 picks went 0-2 against the spread, with a $14 loss to the bankroll. Here are the season to date results:
  • Against the Spread: 8-13-1
  • Starting Bankroll: $1,000
  • Current Bankroll: $741 (-26% ROI)
Here is the week by week performance:

weekbetswonstarting
bankroll
amount betprofitsending
bankroll
4 2 0 $1,000 $268 (26.8%) ($268) $731
6 1 1 $731 $32 (4.5%) $29 $761
7 3 3 $761 $130 (17.1%) $118 $879
8 3 1 $879 $70 (8.1%) ($12) $867
9 7 2 $867 $166 (19.2%) ($66) $800
10 4 1.5 $800 $95 (11.9%) ($45) $755
11 2 0 $755 $14 (1.9%) ($14) $741

Sunday, November 17, 2013

Underdogs Shouldn't Play for Overtime


In week 9 of the NFL season, the Buccaneers nearly pulled off an historic upset playing on the road against the heavily favored Seahawks. The Bucs were a 15.5 point underdog, yet somehow found themselves leading 21-0 with just over two minutes to go in the first half. Going back to 1989, only three NFL teams have won a game as a 15.5 point or greater underdog.

When playing as an underdog, there are a couple things a team can do to maximize its chances of winning:
  1. Go for high variance plays (surprise onside kicks, going for it on 4th and short, two point conversions, deep passes, etc.)
  2. Shorten the game when possible (when you're the underdog, the house will eventually win if you stick around long enough, so cash out while you can)
Credit Coach Schiano for calling for a surprise onside kick in the second quarter. The Seahawks recovered the kick (just barely), but it was still a smart call. Late in the game, Schiano had another opportunity to make the right call....

NBA Win Probability Calculator

Classic shot of the ENIACThis past summer, I rolled out my initial attempt at a win probability model for the NBA (introductory post | the insanity that was Game 6 | graphs for all playoff games | win probability added). Since that time, I have refined the model somewhat via more rigorous cross-validation of the model parameters. And while I may still have some tinkering to do, I'm ready to share a beta version of an online Win Probability calculator.

Much like the Win Probability tool from Advanced NFL Stats, this tool allows you to input the game state (time remaining, margin, possession) and it will return the win probability of said game state.

So what's the point? From my perspective, a win probability model has three main potential uses:

Saturday, November 16, 2013

Playoff Implications - Week 11

Here is your weekly cheat sheet for NFL games with playoff implications. The purpose of this feature is to highlight games that have a big impact on the playoff picture (see this post for background). I can summarize the total impact a game is expected to have, as well as how it affects each particular team.

The main change from last week is that I am now filtering out results that aren't statistically significant. I am using the Fisher Exact Test for this purpose, with a significance level of 95%.

Ranking Week 11 Games by Leverage

The table below ranks the week 11 games by total leverage. Leverage in this context is a measure of both how uncertain a game's outcome is (games between evenly matched teams have higher leverage) and how much the playoff picture swings as a result of that outcome.

Wednesday, November 13, 2013

Turnover Index - Week 11

Here are the Turnover Index picks for Week 11. The Turnover Index is a simple betting strategy based on the theory that the market overvalues defensive turnovers when judging team strength. See here and here for more background.

Week 10 results

Once again, it was not a good week. Week 10 picks went 1-2-1 against the spread, with a $45 loss to the bankroll. One callout is on the Texans-Cardinals game. The general consensus seems to have the closing line at 3.5 or 4 points in favor of the Cardinals. The Cardinals won by 3, meaning the bet on the Texans should have covered. But my official source for lines and stats is sportsdatabase.com, which has the closing line at -3. I don't want to go down the rabbit hole of double-checking every single game, so I'm sticking with the sportsdatabase numbers with the assumption that any discrepancies even out in the long run. Here are the season to date results:
  • Against the Spread: 8-11-1
  • Starting Bankroll: $1,000
  • Current Bankroll: $755 (-25% ROI)
Here is the week by week performance:

weekbetswonstarting
bankroll
amount betprofitsending
bankroll
4 2 0 $1,000 $268 (26.8%) ($268) $731
6 1 1 $731 $32 (4.5%) $29 $761
7 3 3 $761 $130 (17.1%) $118 $879
8 3 1 $879 $70 (8.1%) ($12) $867
9 7 2 $867 $166 (19.2%) ($66) $800
10 4 1.5 $800 $95 (11.9%) ($45) $755

Saturday, November 9, 2013

Playoff Implications - Week 10

Here is your weekly cheat sheet for NFL games with playoff implications. The purpose of this feature is to highlight games that have a big impact on the playoff picture (see last week's post for my first attempt). I can summarize the total impact a game is expected to have, as well as how it affects each particular team.

The main change from last week is that I am now filtering out results that aren't statistically significant. I am using the Fisher Exact Test for this purpose, with a significance level of 95%.

Ranking Week 10 Games by Leverage

The table below ranks the week 10 games by total leverage. Leverage in this context is a measure of both how uncertain a game's outcome is (games between evenly matched teams have higher leverage) and how much the playoff picture swings as a result of that outcome.

Friday, November 8, 2013

Could a playoff seed ever be determined by a coin flip?

Warning: Pointlessness ahead.

In order to produce my playoff seed projections for the NFL, I had to do some rather tedious coding of the tiebreaker rules. For example, here are the divisional tiebreaker rules when two teams have the same win-loss-tie record:
  1. Head-to-head (best won-lost-tied percentage in games between the clubs).
  2. Best won-lost-tied percentage in games played within the division.
  3. Best won-lost-tied percentage in common games.
  4. Best won-lost-tied percentage in games played within the conference.
  5. Strength of victory.
  6. Strength of schedule.
  7. Best combined ranking among conference teams in points scored and points allowed.
  8. Best combined ranking among all teams in points scored and points allowed.
  9. Best net points in common games.
  10. Best net points in all games.
  11. Best net touchdowns in all games.
  12. Coin toss
Most casual fans are aware of the implications head-to-head, divisional records, and conference records have for playoff seeding. But things get pretty esoteric as you move further down the list. I had to look up what "Strength of Victory" meant (it's the combined winning percentage of the opponents you beat), and frankly had to make a bit of a guess as to what "combined ranking" meant for #7 and #8. At the very bottom of the list is "Coin Toss", which I even went through the trouble of simulating with a random number generator.

But could the "Coin Toss" scenario ever come in to play? (doubtful) Would ESPN televise it? (probably) Should they have replaced "Coin Toss" with "Dance Off"? (definitely)

Wednesday, November 6, 2013

Turnover Index - Week 10

Here are the Turnover Index picks for Week 10. The Turnover Index is a simple betting strategy based on the theory that the market overvalues defensive turnovers when judging team strength. See here and here for more background.

Week 9 results

It was not a good week. Week 9 picks went 2-5 against the spread, with a $67 loss to the bankroll. Here are the season to date results:
  • Against the Spread: 7-9
  • Starting Bankroll: $1,000
  • Current Bankroll: $800 (-20% ROI)
Here is the week by week performance:

weekbetswonstarting
bankroll
amount betprofitsending
bankroll
4 2 0 $1,000 $268 (26.8%) ($268) $731
6 1 1 $731 $32 (4.5%) $29 $761
7 3 3 $761 $130 (17.1%) $118 $879
8 3 1 $879 $70 (8.1%) ($12) $867
9 7 2 $867 $166 (19.2%) ($66) $800

Sunday, November 3, 2013

Playoff Leverage - Week 9

Earlier this week, I added playoff seed projections to my daily NFL rankings, which are based on simulating the remainder of the season 10,000 times. In addition to projecting playoff seeds, I can take the same simulation dataset and use it to see which games have the biggest impact on the playoff picture.

You can find a similar feature at Advanced NFL Stats, which highlights the high leverage game of the week (it's GB-CHI according to their model). This post attempts to take a more detailed view, looking at how each particular game affects all teams, not just the two participants.

A Big Week for Baltimore

My playoff simulations indicate that the defending champion Ravens have a 29% chance of making it to the playoffs at this point. This week's matchup against the Browns will have a big impact on those chances. If the Ravens lose, their playoff hopes drop to 16%. And if they win, they increase to 39%. That swing, coupled with the fact that the game is fairly evenly matched (Baltimore has a 56% chance of winning at Cleveland), makes this the highest leverage situation of Week 9.

Note that high leverage doesn't just mean a big potential swing in outcome. If I buy a lottery ticket, there is a big difference between me winning and losing. But since the probability of winning is so small, the leverage is small as well. This article from Tom Tango explains the concept (fyi - I am using the recipe #2 version of the leverage calculation).