Yeah, I think this is the one sport where you either have to have discipline or you're sunk. And this isn't to pile on Astros. He's a great guy on a good run. It's just that this sport is unforgiving. There is no rhyme or reason when you're dealing with individuals. How many people piled on Nadal in live betting when he was down a set because they could get a better price than pre match? Or Simon? Just like when people pile on "sure favourites" pre match because of rank, H2H ( on different surfaces mind you), etc... I love those people and thank them for their contributions as that makes my dog wins that much more profitable.
However... there is no guru with tennis betting. Bet on -250 fave and win. Bet the next -350 and lose. GL. Those who are making money on this sport consistently (ie over a year or more) are either spending a hell of a lot of time following every single person playing on the Tour (challengers included) and have excellent discipline/mm, getting lucky with big smashes or are arbing. That's it. The rest of us hope to have a profit at the end of the year.