Why bowlers shine the ball by rubbing?

Shining the ball basically keeps the ball hard and subject to what you call 'swing'. Shiny balls swing in the air whilst travelling at speed. As the game goes on and the ball receives consistent impact on the surface, the ball will most definitely lose its shine, and thus one side of the ball will be emphasised and taken care of. This is done in order to acheive the so called Reverse swing! For more, refer www.planetcricket.com forums Hope you got wat i meant!

Yeah it really helps the spinners very much. If you have noticed well new balls will not turn at all for spinners. The reason being shiny balls tend to move straight even after pitching. But as the match progresses, the shiny part becomes old so that the spinners able to turn the ball well. And importantly the ball is rubbed only on one just. Therefore the ball can be turned or bowled straight based on which side of the ball pitches. This greatly confuses the batsmen.

Hello friend, Bowlers like to shine one side of the ball and keep the other half as dirty and scuffy as possible. The reason is that when the ball is bowled with the seam upright, one half of the ball presents lesser friction to the air than the other(dirty) part. As a result, both the halves of the ball tend to move with different speeds but as this cannot really happen, the ball starts swinging towards the shine or away from it, depending on whether it is normal swing or reserve swing. I don't think it helps the spinners as they bowl it much slower.

yeah it really helps!! by the shining side i think the ball turns and confuse the batsman!! also they rub on the pants when there is any dew on ground got on to the ball!!