Rolling Disparities In Baseball 136 views

If you pay attention to any of the national baseball writers or the major magazines, I'm sure that you have read experts lament about the quality of baseball being played and the disparities between major and minor market teams. This does reflect in sports betting. The data below shows the number of games being played annually at lines between -200 and -299, large favorites, and the average line for these games.

2004 310 -226
2005 282 -222
2006 239 -225
2007 257 -222
2008 228 -223
2009 241 -226
2010 285 -223
2011 188 -222
2012 198 -222
2013 218 -227
2014 121 -222
2015 151 -224
2016 263 -227
2017 265 -225
2018 392 -229
2019 310 -230

My first observation is that the number of games played between these lines started at just over 300 15 years ago, fell gradually, and has increased again in the past two years. This suggests that the number of big disparity games is on the increase. The average line for these games has also increased as it hit -230 this season: they are getting more expensive. So clearly the disparity of talent between teams is growing as more and more games are being played at big lines.

The other observation is this. If someone had hired a group of chimpanzees 6 years ago and taught them to just bet every favorite in this range, the chimps would have had a positive return in 5 of the last 6 years. At the end of this season, the chimps will be sitting on a very large pile of bananas, earning over $8K so far in just this season. Please be assured that I will be watching this group very, very closely over the first couple of months of the 2020 season to see how this develops.

Good Hunting, John


Michael awarded 200 tokens for this post.

tortoisewins awarded 200 tokens for this post.

Nice piece of info, but I'd rather stick to no less than -150. If you had 365 bets a year at -150, you would be 0% if you hit 60%. So imagine what you'd have to hit betting these huge faves to breakeven.
Also wouldn't go any worse than -2.5 for fottball or -3 for NBA.


If one can assume that overall record is a good indication of the general strength of teams, there is no doubt that the MLB has reached a point of significantly increased games being played between haves and have nots. From an empirical perspective, the typical standard deviation of win% has risen significantly over the past 6 years and listed below are the yearly percentage points deviation from average within that timeframe. The difference at first may seem small, but when extrapolated over a typical 162 game season amounts to a difference of 6 full games of parity between 2019 and 2014. It obviously makes sense as John alluded to that betting lines have indeed increased and is a by product of these numbers.

2019 - .0986

2018 - .0904

2017 - .0712

2016 - .0662

2015 - .0644

2014 - .0593


Captian, I must tip my hat, recognizing your mad statistical skills. Can you show me how to derive the standard deviations that you displayed?


Hi John,

If you're familiar with Excel, insert the win percentages for every team in a column for a given year, then in any other blank cell on the page use the Excel standard deviation formula function to display the SD number for any given year.

You can do this also on any statistical calculator but after my many years of punching numbers into a calculator, I prefer the easier way.


Thank you. Had a couple of trusted capper friends help me out with the pointers. Bankroll is also important. $20 a month, plus I put 10% of my pay each week into a 2nd bank acct for Futures bets.
Use to bet blindly on every game, but it doesn't profit.


Interesting, thanks for the post. I started betting baseball in 2005, at the time I had no idea it was the golden age of dogs (see my SDQL for simply dogs greater than 125) "D and line>125" below).. I started to struggle after a few years and never could find my "groove". There was a trend developing that I got wise to eventually and as you can see 2019 is already the worst season for dogs in the KS database. This year I've bet more favorites than ever and I turn my nose up every time I submit a bet with a minus sign in front. I've learned the hard way over the years that trends just come and go, maybe baseball was only being bet by sharps so the books got wise, I don't know why but the numbers are clear, its slim pickins on doggies so I've been pushed into betting more favorites. There are still some good doggie plays to be had but the other problem is they all hover around 40% WP and that inevitably leads to deep and long losing streaks. I still manage to have +93 units with an AOP -104 tracking here since June 1, 2019 but its not easy to avoid the heavy favorites. Trends are my friend but I long for the days where +150 dogs hit on the regular; sure enough they will come back, maybe, probably, hopefully!


Thanks for the data. It still surprises me that people have guidelines that are based on what worked years ago, rather than adapting to an obviously changing environment. We must be constantly testing the water to see how things are changing.


Captain, thanks again. You are right. Why screw around when excel can determine standard deviations and even produce histograms if you wish.


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