How the hot start Tigers have actually been unlucky

tigers_cluster_luckIn my latest article for the Detroit News, I ask whether the Tigers have gotten lucky early this season.

There are many ways luck can affect a baseball team, but I look at cluster luck here. To read why the Tigers have gotten unlucky in this department, click here.

This doesn’t mean the Tigers will continue to score runs at their current torrid pace. As a commenter pointed out, they have a high batting average on balls in play, which will regress as the season progresses.

However, we can rule out cluster luck early this season. The article has numbers for all MLB teams through Sunday. The list below gives cluster luck through Tuesday’s games.

The first number gives total cluster luck, while the numbers in parentheses gives a breakdown on offense and defense. In all cases, a positive number implies good luck.

1. Texas, 19.32. (11.62, 7.70).
2. New York Mets, 16.55. (9.48, 7.08).
3. Arizona, 14.95. (5.89, 9.06).
4. Toronto, 14.45. (14.83, -0.38).
5. Los Angeles Angels, 10.53. (9.16, 1.36).
6. Pittsburgh, 8.72. (11.18, -2.46).
7. San Diego, 7.27. (3.44, 3.82).
8. Boston, 4.79. (11.96, -7.17).
9. St. Louis, 4.78. (-3.91, 8.69).
10. Atlanta, 2.88. (0.86, 2.02).
11. Philadelphia, 2.09. (-3.17, 5.25).
12. Colorado, 1.46. (-1.37, 2.83).
13. New York Yankees, 1.16. (3.35, -2.19).
14. Minnesota, 1.16. (4.00, -2.85).
15. Kansas City, 0.88. (2.89, -2.01).
16. Cleveland, 0.08. (0.23, -0.16).
17. Cincinnati, -1.29. (3.19, -4.48).
18. Chicago Cubs, -2.25. (1.66, -3.91).
19. Chicago White Sox, -3.76. (-2.57, -1.19).
20. Houston, -5.11. (-5.89, 0.78).
21. Washington, -5.47. (-0.72, -4.75).
22. Oakland, -6.50. (1.67, -8.17).
23. Miami, -6.76. (3.40, -10.16).
24. Detroit, -8.86. (-8.23, -0.63).
25. Milwaukee, -9.15. (2.44, -11.59).
26. San Francisco, -10.72. (-13.43, 2.71).
27. Seattle, -11.66. (-3.98, -7.68).
28. Baltimore, -12.61. (-0.99, -11.62).
29. Los Angeles Dodgers, -15.28. (-13.80, -1.48).
30. Tampa Bay, -15.53. (-3.77, -11.76).

Detroit’s cluster luck has gotten worse on offense but gone back to neutral on defense.

NBA playoff win probabilities for 2015

nba_playoffs_2015You want to know which team will win the NBA playoffs.

Can Golden State continue their magical season and win the championship? Or will another contender like San Antonio or Cleveland steal the crown?

I had a tough time calculating playoff win probabilities this year because of Cleveland and San Antonio. Both these teams started the season slow.

However, San Antonio has an aging core that won the title last season, and Cleveland has the best player on the planet in LeBron James.

I calculated win probabilities based on my NBA team rankings that take the margin of victory in regular season games and adjust for strength of schedule. It gave Golden State a 56% chance to win the title, which seemed too high.

As an alternative, I estimated the late season form of San Antonio and Cleveland through the betting markets. I took the closing point spread in all games since late February and applied my ranking algorithm to adjust for strength of schedule.

In these market rankings, Golden State is still the best team. However, their rating is only about one point better than San Antonio and Cleveland. The difference was more than 3 points in my team rankings.

With the market rankings, Golden State has a 39.5% to win the NBA championship. They benefit from a first round matchup between San Antonio and the Los Angeles Clippers, their toughest competition in the West.

To see all of my NBA win probabilities, check out this interactive visual from Andrew Phillips of Chartball. Hover over a team to see its chance to advance through each round. Hover over a circle to find the likelihood that each team wins a round.

This list gives the title chances for all 16 NBA teams in the playoffs.

1. Golden State, 39.5%.
2. Cleveland, 26.8%.
3. San Antonio, 14.3%.
4. Atlanta, 5.2%.
5. Los Angeles Clippers, 5.1%.
6. Houston, 2.8%.
7. Memphis, 1.7%.
8. Chicago, 1.2%.
9. Toronto, 1.0%.
10. Portland, 0.8%.
11. Washington, 0.7%.
12. Dallas, 0.5%.
13. Boston, 0.1%.
14. New Orleans, 0.1%.
15. Milwaukee, 0.1%.
16. Brooklyn, 0.1%.

I will update the interactive visual the morning after each day of games, so check back for the latest win probabilities.

The Power Rank best at predicting the 2015 NCAA tournament

Screen Shot 2015-04-13 at 12.26.06 PMYou have a lot of choices for predicting the NCAA tournament.

My probability for each team to advance through each round appear in this interactive visual. However, these other quants perform the same calculation.

Which tournament win probabilities were the most accurate in 2015?

Reuben Fisher-Baum of FiveThirtyEight took a quantitative approach to determining which tournament predictions were most accurate. He looked at how a predicted probability deviated from the actual result in the tournament.

For example, my numbers gave a 70.7% chance for Duke to advance to the Elite 8. Since Duke did advance to that round, we assign that result the number 1.0. The square of the deviation, or (1.0 – 0.707) squared, gives a Brier score for that prediction. For an event that happened, a larger probability is better, so a lower Brier score implies a better prediction.

From FiveThirtyEight’s analysis, The Power Rank had the most accurate 2015 tournament predictions.


Duke’s run through the tournament helped out my method rise to the top. Of all the models, my numbers had the highest probability for Duke to advance to the Sweet 16 and every round after that.

FiveThirtyEight gave this very kind conclusion.

Given that Duke is traditionally undervalued in bracket pools, fans who built their brackets on The Power Rank’s numbers likely had a pretty good tournament.

Indeed, some people did have such success.

Ryan Peters bought my book on how to win your pool and knew the importance of picking a value champion, or a team with a high win probability overlooked by others in his pool. He chose Duke and sent this tweet on the eve of the championship game.

I had Duke ranked third in my team rankings heading into the tournament. They got credit for playing a tough ACC schedule which included Virginia, Notre Dame (3 times), North Carolina (twice) and Louisville, all top 20 teams in The Power Rank. These strength of schedule adjustments moved Duke higher compared to other rankings.

The Power Rank came out on top this year, but don’t expect these results every year against stiff competition. One tournament represents a small sample size of 67 games. Had Kentucky won the tournament like my numbers expected (38% win probability), the results could have been different.

Can Justin Verlander stay healthy in 2015?

Screen Shot 2015-04-07 at 7.07.07 AMJustin Verlander is a huge question mark for the Detroit Tigers. The former Cy Young winner has a triceps strain in his pitching arm and won’t make his first start until April 12 at the earliest.

Will this injury derail his season? Or is this injury a fluke that will seem like a distant memory when Verlander throws his 200th inning in September?

In my latest column for the Detroit News, I use the injury analytics of Jeff Zimmerman of Fangraphs to analyze Verlander’s situation. I also look at the other starters for the Tigers.

To read the column, click here.

John Calipari is a better tournament coach than Tom Izzo

calipariJohn Calipari evokes many different emotions in sports fans.

If you’re a Kentucky fan, you probably love Calipari. In six years as coach, he has won a national championship, and his 2015 team might win another with an undefeated record.

If you’re not a Kentucky fan, Calipari represents all that’s wrong with college basketball. His teams at Massachusetts and Memphis had to vacate wins during Final Four years because of NCAA rules violations. While the NCAA never found Calipari guilty of anything, it seems unlikely he knew nothing about the infractions.

Moreover, Calipari pisses off his colleagues. At a press conference, he got former Temple coach John Chaney so mad that Chaney attacked him, yelling “I’ll kill you.” Yes, this really happened; check out the video.

Numbers reveal a third side Calipari: he’s an amazing tournament coach. This article looks at how teams perform in the tournament compared with a regular season baseline. With a high degree of statistical certainty, Calipari’s teams play better in March than the regular season.

Calipari’s ability to get more out of his teams during the tournament is neither a typical part of his narrative nor the story in which I was originally interested. Michigan State coach Tom Izzo usually gets praised for his excellent coaching in March. I didn’t believe this conventional wisdom, so I dug into the numbers.

Comparing tournament performance with the regular season

To test Michigan State’s play in the tournament, I compared their margin of victory in the post season with expectations from the regular season.

For a regular season baseline, I used my college basketball team rankings at The Power Rank. Developed from my Ph.D. research in statistical physics, this algorithm takes margin of victory and adjusts for strength of schedule.

From 2002 through 2014, the higher ranked team in my pre-tournament rankings won 71.3% of games. In addition, the rankings provide a predicted margin of victory in each game. We’ll use this prediction as a baseline for tournament performance since, unlike the point spread in Vegas, it makes no preference for Michigan State or any other team in March.

For all tournament games from 2012 through 2015, I looked at Michigan State’s actual margin of victory compared with The Power Rank’s prediction. For example, in 2015, Michigan State beat Virginia by 6 points and exceeded the baseline prediction by 12.1 points. In 43 games tournament games, Michigan State has exceeded their expectation from The Power Rank by an average of 2.07 points.

Two points might not seem like a lot, but it’s a huge jump in performance. If the betting markets favor a college basketball team by 2 points, this teams wins the game 58.4% of the time, much more than the 50% for a game with a zero point spread.

Are these results statistically significant?

However, we can’t just assume that Michigan State performs better in the tournament based on this 2.07 points. There’s randomness in this estimate. We don’t know whether Michigan State performed at the same level as the regular season and got lucky by two points a game. Or Michigan State could be 4 points better than the regular season and got unlucky in the tournament.

Statistics gives us tools to account for the randomness in this estimate. A t-test, a method first developed at the Guinness Brewery, provides a probability that this estimate of 2.07 points is better than zero. This test, using this nifty calculator, gives a 92.6% confidence that Michigan State performs better in the tournament. (For those who want to check my work, the standard deviation of sample mean over 43 games was 1.40 points.)

I was wrong. The numbers suggests a high likelihood that Tom Izzo’s teams perform better in the tournament. Conventional wisdom wins this time.

The greatness of John Calipari

With the code to perform this test for Tom Izzo, I decided to repeat the test for the other Final Four coaches in 2015.

Duke coach Mike Krzyzewski has a reputation for getting the most of his players in March. However, since 2002, they have performed 0.41 points worse than The Power Rank’s expectation from the regular season.

Wisconsin coach Bo Ryan did slightly better than Krzyzewski in the tournament. However, his teams still performed 0.21 points worse than expected over 37 games.

John Calipari was a different story. During his years at Kentucky (2010 to present), his teams have performed 3.86 points better than their regular season expectation. Even with the smaller sample size than the other coaches (25 games), we can be 98.1% sure Kentucky has played better in the tournament.

Calipari also coached at Memphis before taking the Kentucky job. From 2002 through 2009, his Memphis teams exceeded their regular season expectation by 1.38 points in 20 tournament games.

It’s probably best to combine the tournament performances of Calipari’s Kentucky and Memphis teams, which gives a 2.76 point improvement over 45 games. That implies a 96.8% confidence that his teams play better in the tournament. In addition, Calipari’s tournament improvement is 35% larger than Tom Izzo’s improvement.

The following list summarizes the difference in tournament performance from the regular season since 2002.

  • John Calipari: + 2.76 points per game.
  • Tom Izzo: +2.04 points per game.
  • Bo Ryan: -0.21 points per game.
  • Mike Krzyzewski: -0.41 points per game.

For the 2015 Final Four, the main story should be John Calipari’s greatness as a tournament coach.