In short, I'm thinking no, but my mate has had quite a bit of success betting on two different outcomes that he likes to call an Arb, even though it's not technically an Arb.

What he does is backs the underdog at $2.40 and the favourite at -1.5 also at $2.40. Obviously if the favourite wins by exactly one run, this is the way he loses, but it rarely happens for him. He picks and chooses which games to bet on. In reality he is only getting odds of $1.20 that the favourite doesn't win by exactly one run, and I haven't looked into it enough to see if his success is sustainable long term.

The one thing in his favour is he has various accounts and he bets on the agencies offering the best odds.

Is there anyone who can prove that this success is not sustainable long term by providing historical data? Basically if the favourite wins by exactly one run 20% of the time, he loses. Any less than that, and he wins. At first thought I was thinking there is no way the favourite wins by exactly one run in at least 1/5 matches, but history must says it does happen, otherwise the books wouldn't open with those odds.