Re: How do you differentiate "Not Trying / Tanking" from "Tiredness / Out of Steam"?
Seems like there is more concern among ATP players than WTA players and tales and rumors about men tanking matches have been around for at least 20 to 30 years. Sampras once said he beat some player "6-2, tank and tank."
Among women, it seems to me walking around listlessly would be a dead give away, but since there are so man EU's in women's matches, it would be a lot easier for a woman player to just spray a few more balls than normal if you wanted to tank a match.
I don;t think there is much of that, though. The one thing that is for certaiin is that once gambling gets involved, the gamblers are going to try eventually to find a way to fix matches. It happened in baseball and basketball and probably in tennis, too.
FYI, there were rumors that Bobby Riggs, a notorious gambler and hustler, tanked the match against BJ King, because he had money down on her through dummy betters.