[jeesh]

Heres another interesting post i found on the topic

In terms of wickets, New Zealand's Daniel Vettori was the most successful left-arm spinner in the history of the game. He has 345 Test wickets from 105 Tests at an average of 33.98.

That left-arm spinners are not successful is a debatable point. Remember that left-handed bowlers are rare in the first place. For example, Wasim Akram is the only left-arm bowler with over 400 Test wickets. Does that mean that left-armers are not successful? Given that there are hardly left-arm bowlers, the probability of one of them storming the charts like Muralitharan or Warne is pretty rare.

In cricket's history, there have been some good left-arm spinners like Bishan Bedi. One other possible reason is that finger spin is not as effective as wrist spin. Muralitharan is an exception, but to call him a finger spinner is to undermine his talent. Muralitharan could rotate his wrists and his shoulders, so he was really a finger spinner who bowled with a lot of wrist action.

There are very few slow left arm unorthodox bowlers (left arm wrist spinners), so left arm finger spin is the dominant bowling style of left-arm spinners. If we discount Murali (who was a prodigy and biomechanical masterpiece) then Harbhajan Singh is the most successful finger spinner with 406 wickets from 98 matches. The reason for finger spin being less successful than wrist spin is because the ball doesn't turn as much and wrist spinners generally do more with the ball in the air and off the pitch. Also, batsmen can usually see the ball well with a finger-spinner's action, whereas they find it harder to pick the wrist spinner's deliveries.

This is why Murali's wristy action gave him an advantage. Batsmen just could not see what he was doing with the ball most of the time. Even Brian Lara, who played Murali with aplomb, suggested that he didn't really pick Murali. However, he was able to see when Murali would get discouraged and it became easier to play a deflated, discouraged Muralitharan. This is where Lara said that Shane Warne had the edge, because Warne always believed he'd get his man and never let his shoulders drop.

If wrist-spin is more effective than finger spin, you'd think that the chinaman bowlers (slow left arm unorthodox) would have more success. However, the chinaman bowlers turn the ball from off to leg (just as an offspinner). They'd need to bowl to more left-handers to really create more problems. Chinaman bowlers are generally far less successful than leg break bowlers, who turn the ball from leg to off.

Source: http://answers.yahoo.com/question/in...5072502AAVY1PS