Which WTA players are the most reliable favourites?

People love betting on the favourite in any sport. It is only natural – the favourite is the most likely selection to win. However, simply backing the favourites blindly is not necessary a profitable strategy – in fact, it will rarely be a profitable strategy.

The idea of favourite bias has been much discussed. Favouritism bias is where gamblers tend to overvalue outsiders and undervalue favourites. In other words, they value outsiders more than expected, given how often they actually win, and they value the favourites less than expected, given how often they actually win. This might suggest that there could be some worth in looking to back favourites.

In tennis, different players react in different ways to being the favourite. As the favourite, we should expect the player to win, usually they will be the better player or will prefer the surface – hence the favouritism. However, we find that there are a number of players that struggle under the tag of favourite. Similarly, other players enjoy being the fancied player and are very efficient at getting the job done when they should.

Silvia Soler-Espinosa proved a surprising effective favourite for punters

Another aspect to take into consideration is that certain players are very popular with the gambling public. If a certain player is popular, we often find that the odds on them winning are shorter than they should be. People drive the price down on the exchanges simply because they like that player, misrepresenting their true price. We shall look at several examples of this later on.

For those that know a bit about gambling, this section can be skipped. However, as a brief explanation, in each match, odds are available on both players, represented as a decimal. This decimal can be converted into a percentage that represents the implied chance of each player winning the match. For example, in the Australian Open final between Victoria Azarenka and Li Na, the odds on Azarenka were 1.71 and the odds on Li were 2.313. Taking the reciprocal of these, we get the implied percentages – Azarenka has a 58.5% chance of winning the match, while Li has a 43.2% chance of winning. The immediate thing to note is that the two percentages do not add up to 100%, rather to 101.7%. The additional percentage is the overround that the bookmakers add on top to make their profits. Placing a £10 bet on Azarenka at 1.71 would return £17.10, meaning profits of £7.10. Similarly, the same £10 on Li Na would return £23.13, a profit of £13.13.

Looking at the returns on stakes that each player would return over a period of time gives us an idea of how they perform as a favourite, or at least, whether they are overrated or underrated as a favourite by the bookmakers. The odds for each match were taken as the closing Pinnacle odds.

We find that over the past 12 months, the most profitable favourite in the WTA top 100 is the Spaniard, Silvia Soler-Espinosa. If you had been betting on her blindly as the favourite in every match over the past year, you would have seen a return of 40.8% on your stakes. To put this in context, she played 21 matches as a favourite during this period. If you had placed £10 on her in all of those matches, you would have staked a total of £210. You would have seen a profit of £85.68 on those bets. Certainly not a bad return.

She is followed by the world number 29, Elena Vesnina. The Russian would have returned a very impressive 29.0% on total stakes. Having started 26 matches as favourite during this period, £10 on every match would have seen a total stake of £260 and profits of £75.40.

The table below shows the top 10 most profitable players in the top 100 by percentage returns on stake:

Player	World Ranking	Percentage Return	Total Matches as Favourite	Total Profit on £10 stakes
Silvia Soler-Espinosa	64	40.8%	21	£85.68
Elena Vesnina	29	29.0%	26	£75.40
Venus Williams	22	27.4%	31	£84.94
Kirsten Flipkens	23	26.6%	38	£101.08
Ayumi Morita	43	22.5%	29	£65.25
Kaia Kanepi	37	21.0%	19	£39.90
Aleksandra Wozniak	66	19.5%	20	£39.00
Maria-Teresa Torro-Flor	84	19.4%	42	£81.48
Alize Cornet	33	14.5%	35	£50.75
Mallory Burdette	89	14.3%	32	£45.76

Between them, these ten players played 293 matches as the favourite in the past 12 months. Had you placed £10 on every single one of those matches, you would have staked £2,930. However, you would have seen profits of £669.24. In others words, you would have received a 22.8% return on your initial investment. Far better than you would get in the bank.

As an aside, there is also an interesting trend at the top of the rankings. The top 3 players often go off as very short favourites in the majority of their matches. Many people are very wary of backing short priced favourites, however their figures would suggest otherwise. Serena Williams would have returned 7.3% as favourite over the past twelve months, while Maria Sharapova and Victoria Azarenka would have returned 11.6% and 8.3% respectively.

However, while some players return solid profits as a favourite, there are plenty of players that it is worth avoiding. Whether they struggle under the burden of being the favourite, whether they regularly tank matches, or whether they are simply overrated by the bookmakers and gambling public, they tend to lose punters money as favourites.

The table below shows the players to avoid:

Player	World Ranking	Percentage Return	Total Matches as Favourite	Total Loss on £10 stakes
Daniela Hantuchova	75	-28.6%	28	-£80.08
Petra Martic	91	-27.8%	12	-£33.36
Sabine Lisicki	47	-26.4%	26	-£68.64
Coco Vandeweghe	94	-23.4%	21	-£49.14
Lucie Hradecka	58	-22.2%	19	-£42.18
Tamira Paszek	31	-20.5%	16	-£32.80
Andrea Hlavackova	76	-18.4%	26	-£47.84
Jie Zheng	49	-18.3%	22	-£40.26
Yaroslava Shvedova	38	-17.1%	26	-£44.46
Misaki Doi	88	-15.4%	29	-£44.66

Between them, these players played a total of 225 matches as the favourite over the past twelve months. If you had put £10 on each of these matches, you would have staked a total of £2,250. You would have lost £483.42, which works out at 21.5% of your total stakes.

Other notable players that crop up fairly low down the list are the likes of Mona Barthel (-15.1%), Yanina Wickmayer (-14.1%), Melanie Oudin (-10.4%), Julia Goerges (-9.0%) and Laura Robson (-6.7%).

Coming back to our earlier mention of popular players, we can see an interesting trend. The likes of Julia Goerges, Mona Barthel, Daniela Hantuchova, Sabine Lisicki and Laura Robson are all players that are popular with the punters. It is not uncommon to see these players shortening in the betting ahead of their matches as gamblers start to stake their money on the events.

Julia Goerges always proves popular with punters, but it is
unwise to side with her as a favourite

We also see two of the American hopefuls, Melanie Oudin and Coco Vandeweghe, cropping up on this list. Both these players have been much hyped over the past few years as the next big things in American tennis. It would appear that this hype has caused punters to overrate their actual abilities. As favourites at the given odds, both these players would have lost you a reasonable amount of money.

A future article will look more closely at how these players perform as an outsider, which should enable us to draw a few tentative conclusions. It could be that certain players struggle as the favourite, but thrive as the outsider. From this, we might be able to conclude that they struggle with the pressure of being the favourite, while they enjoy the freedom that comes with the lack of expectation as an outsider.

Conversely, we may discover that the same players show strong negative returns as an outsider as well. If this turns out to be the case, we might be able to conclude that their ability is misrepresented amongst bookmakers and gamblers. They are perceived to be better players than their true abilities suggest, in which case, their odds will be too short at all levels, whether the favourite or the outsider.