When Imran Tahir first played for South Africa he was a little wayward used to bowl short pitch deliveries and full tosses quite regularly. But lately he has been very accurate and has been spinning the bowl and also bowling googly at ease. He even troubled left handers in WT20 because of his accurate bowling. I think South African system has helped him develop as a good bowler. He is not only handled by professional board and management unlike Pakistan but is also managed by a world class bowler. His improvement is clearly to be seen and i doubt he would have been the same bowler had he played for Pakistan where coaches and board would have destroyed him as a bowler. But now alongside Steyn he is their main bowler in limited overs Cricket!