There's been a lot of fuss over the years about match fixing, tanking, lack of best effort and the like in tennis. The 2008 report issued in the aftermath of the infamous Davydenko match is required reading for all tennis punters (see link in Useful Links section). It notes, quite rightly, that there are shades of grey. As punters we need to be aware that circumstances exist which means a player may not be at her best, or may not be about to give of her best. That's all part of the fun.
There is one sort of tank that I've come to believe warrants careful consideration among the betting community, and that is the lucky loser tank in qualifiers. It isn't mentioned in the 2008 report because markets were not offered on qualies at that time - it's only within the last year or two that markets have been offered.
If someone in the main draw withdraws then a so-called lucky loser is given the slot, and this is allocated based on the qualies ranking. So it is possible for a player in qualies to start a match knowing there's no need for her to win, as she already has a lucky loser spot in the main draw. This information is generally not available to anyone other than those at the tournament.
One of these occurred last night in Acapulco. Fichmann was the No1 seed for qualies and was odds on to beat Castano. She lost 6-1 6-2 in under an hour. Then the tournament updates the order of play and we see Fichmann down to play Bertens in an hour's time as a Lucky Loser. Pity the punters who backed Fichmann.
Dead rubber markets occur in many sports, but the major difference is
the availability of information to punters before the event. A dead
rubber in, say, a World Cup Group match is known to all, and people can
decide whether to risk betting or not. But whether a tennis player in
qualies has already got a lucky loser spot in the main draw, and hence
does not need to win, is usually known only to very few at the tournament.
I believe there's a case to be made that there should not be markets for qualies for WTA tournaments. Slams are different, as lucky loser spots are allocated by ballot.
Caveat emptor seems a thin defence in this case, as the lucky loser scenario isn't that well known, though once bitten by it I doubt anyone will fall in the same trap again, and give final round qualies involving the top seeds a wide berth.