Analysis of My Tennis Results Over the Last Two Years and How Betting Lines as Early as Possible More than Doubled my Returns

Betting Early and Price Shopping

[This graph] (https://imgur.com/gallery/KKPxdve) shows my units gained and ROI from betting ATP tennis in 2019 & 2020. The blue line is my actual results over 615 bets in that time period. These are the odds I actually bet the matches at. The stats are as follows: 352-250-13, +77.32u, +8.9% ROI, +1.94% CLV, +12.3 average cents of CLV per bet, and I beat the closing line 70% of the time. You can see all my past bets [here] (https://docs.google.com/spreadsheets/d/1XvXPpU4EHQBtrFXm6hqvgrtDn8uPr_p92Fx64Vp49kU/edit?usp=sharing). Note: FWIW, people calculate CLV differently. I calculate it as the % difference in implied probability, some people do the expected value % way.

I decided to chart my returns as if I had made every bet at Pinnacle’s closing line, the red line on the graph. The difference is quite noticeable. My returns betting at the closing line over those same 615 bets are as follows: +35.8u, +4.3% ROI. Getting on lines as early as possible (assuming you’re on the right side) and shopping for the best prices even if its only between 2 or 3 books can make a massive difference in your results. I personally only shopped between BetOnline and Bookmaker as these books are better for tennis, but you could only imagine the insane advantage you could get shopping between 7-8 different books. Obviously many of us on r/sportsbook knew this was the case in theory, but I thought it would be cool for everyone to see the difference it can make over the longer-term: over multiple years and over 500+ bets, the added value from betting early and shopping for the best price will magnify your returns. After all, not many people track their results long enough to see this change. We’re talking about getting only a 12 cent head start on the closing line, doubled my return after 600 picks.


It seems not all Pinnacle closing lines are as efficient as made out to be

I was a bit surprised to see my results at close still had a 4.3% ROI over 600 bets. This return over that sample is beginning to become statistically significant. Pinnacle is known for having some of the sharpest closing lines in the business. Now tennis isn’t on the same level as, say, English Premier league, but what gives here?

[This graph] (https://imgur.com/gallery/UsLEouP) made by Pinnacle charts over 136,000 odds on tennis matches spanning from 2015-2019. As you can see there is an incredibly high degree of efficiency between the implied win % from the odds and the actual win % of those matches. (Note: the blue line is slightly below the yellow as the bookmaker’s margin is not removed). Similarly, [here is your ROI by odds groupings] (https://imgur.com/gallery/I0dAbZf) if you had blindly bet the Pinnacle closing line of every ATP main draw match since 2010. There’s clearly a favorite-longshot bias in play here as underdog ROI’s are in the negative double digits, but it seems Pinnacle’s ATP closing lines are pretty efficient.

Obviously, my results betting at close vs the empirical data of over tens of thousands of ATP matches on Pinnacle are beginning to contradict each other. My opinion is that is that, although it’s true that Pinnacle closing lines are a great, if not the best, estimator of the true probabilities of a tennis match, this is only true ON AVERAGE. As bettors, we have the distinct advantage of being able to select bets where we believe the market is wrong. We don’t have to bet every single match or game. In the span of 2019 and 2020 there were roughly 16,000 ATP and Challenger level tennis matches; I only bet about 3% of them.

It’s certainly not out of the realm of possibility that Pinnacle just fucks up on pricing a small percentage of their bets. On the other hand, a prevailing theory may also be that there is some sort of price anchoring going on between Pinnacle and their customers betting into the line. From [Joseph Buchdahl’s article] (https://www.pinnacle.com/en/betting-articles/educational/how-to-solve-a-problem-like-efficiency-part-two/KS5JTMY67W9XFGGM) on Pinnacle: “Let’s suppose instead that when a price longer than the ‘true’ price is published, it is more likely that it will close still longer than the ‘true’price. Conversely, when a shorter than ‘true’ price is published it is more likely to close still shorter than ‘true’. Why should this be the case? Well, since the ‘true’ price remains unknown, both to the bookmaker and their customers, the actual value of the opener could be hypothesized to act as a kind of anchor or reference point which biases judgement and restricts the magnitude of future movements. Sure, pricing mistakes will be exploited, but possibly not by as much as they should be. That, at least, is the idea” of price anchoring.

He goes on to say: The majority of bettors will probably look at the odds before deciding whether to bet rather than undertaking their own analysis to determine a ‘true’ outcome probability. Thus, when a bettor sees a bookmaker’s price of 2.25, they might take the view that the ‘true’ price is 2.05, and not 2.00. The act of observing the 2.25 may influence their judgement to the extent that they will deviate away from the ‘true’ price and towards the anchor price. A similar argument can be applied to prices shorter than ‘true’.”

So, it’s possible that there is some amount of price anchoring going on, and these closing prices are closing not long enough or not short enough from their fair values. It’s also possible that I’ve just been getting astronomically lucky for the past two years, but we can only guess until I submit more bets.


CLV Matters

Although not all of these closing lines are efficient, my results are better as my CLV improves. See some of [these stats] (https://imgur.com/gallery/R6mK3UL) for reference.

  • When getting positive no-vig CLV: +66.78u, +16.0 ROI% over 291 bets

  • When getting negative no-vig CLV: +10.55u, +2.33% ROI over 324 bets

When my closing line value does not even beat out the bookmaker’s vig, the returns are a measly +10u over 324 bets. When I overcome the juice, my ROI skyrockets to 16% over 291 bets.


Lessons learned / Advice

  • Bet as early as your bet size will allow and shop for the best prices. It will lower the sportsbook’s hold and will vastly improve your returns. This is the easiest way to improve your edge right off the bat. I think my results showed this.

  • Perhaps focus your betting on less efficient markets. Want to bet NFL or NBA for example? Focus on player props, instead of sides and totals. You’re more likely to have an actual edge and are also more likely to find prices way off from the rest of the market

  • If you do decide to dabble in more efficient (hard-to-beat) markets, keep track of your CLV. Once you obsess over beating the closing line you become more price sensitive and more process oriented rather than results oriented. Your focus shifts to accumulating expected value over time that will produce results in the “long-term”, rather than “trying to pick winners.” on a day-to-day basis. CLV isn’t the ultimate proxy for success, there are some exceptions, but the benefits a bettor achieves from making this his / her main focus cannot be overstated.


Anyways, sorry for the long post; hope you enjoyed the read. If you want to follow me this tennis season, I post everything in the Tennis Daily thread. I also have a [telegram channel] (https://t.me/joinchat/T2OET7cTfdoHsZl1) that you can follow so that you get notifications of when I bet. Reddit isn’t always the best medium for sharing plays. The next tournament is in a few weeks with the Australian Open right around the corner. Best of luck!

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