Originally Posted by honestbharani
Again, you are assuming that the ball will never move more than what it moved at impact. An umpire can judge that, hawkeye cannot. And there are 3 or 4 people involved who work on Hawkeye and if and when they get it wrong, the human error there is gonna cause hell of a lot more damage than any umpire's error has. And I understand they do not stop the hawkeye's tracking at some random point and then use the predictive path to compare it on a match to match basis. Which means, all the experimentation and results provided can be of no use, if they had been so much as a 1mm displacement of one of their 6 tracking cameras, which is perfectly possible. And from reading up on the Hawkeye guy's PDF where he has shared his mail communications with Mickey Arthur and some screengrabs, it is even more obvious that they NEVER provide for exaggerated deviations at any point after pitching. They track the ball till impact and extrapolate from there.
The LBW law states that an umpire is supposed to assume that the ball will travel straight on from where the ball strikes the batsman. If he's trying to predict the swing or spin then that's poor umpiring.