No Certainties In Sports Betting
Gamblers will be well aware that that there is no such thing as a certainty and the growth of in-running betting has caused fortunes to be won and lost when incredible results have defied the odds. The recent performance of the Major League Baseball team the Boston Red Sox can be added to that list. The sudden collapse in the team’ performance has even been discussed in the financial press (1) as evidence of the weaknesses of statistical modelling.

The Boston Red Sox failed to make the post-season championship games despite at one point having a 10 game lead over their playoff rivals Tampa Bay Rays. The probability of the Red Sox making the play-off games stood at more than 99%. But the Red Sox proceeded to lose 20 of their last 27 games.
Going into the final game of the regular season both the Rays and the Red Sox still had a chance to extend their season into the play-offs.
The Red Sox were 3-2 up against the Baltimore Orioles as the game entered the ninth and final innings. Throughout the season the Red Sox had not lost a game when leading going into the ninth. On this occasion, however, they contrived to lose 4-3.
Meanwhile, over in Florida, the Rays were being stuffed 7-0 by the New York Yankees in the fifth innings, giving them a less than 1% chance of winning. But in a remarkable turnaround that makes in-running betting so exciting, the Rays hauled it back to 7-6 in the eighth, made it 7-7 in the ninth and went on to win 8-7 in the 12th innings.
The Rays made it to the post-season games. The Red Sox did not.
Writing about the Red Sox’ performance in the Financial Times, John Authers equated the performance of sports teams with financial markets and trying to create a model of future performance: 


“Their high probability of success engendered a flawed overconfidence. And statistical models were flawed in assuming they would keep playing at the same rate, and that the outcome of each game was independent of all others – in baseball, as in markets”.
“And, in markets, models based on a few years when volatility was unusually low and the economy unusually healthy were useless when things turned bad”.
Investors and gamblers alike would do well to remember the small print – “past performance is no guarantee of future results“. 
(1) John Authers ‘Human Factor Can Make A Fool of Risk Models‘ Financial Times, 30 September 2011
(2) Elliott R. Morss The Red Sox Collapse – Why?