I did not see the coverage so cannot comment on their disagreement however when fielding within closer proximity there are considerations the fielder must make.
- Is there an opportunity of a run out?
- Is the wicketkeeper at the stumps or appraching the stumps?
- Is this going to the bowlers end?
- is there someone at the stumps?
- Is the ball return just to get it back to the wicketkeeper / bowler (no runout opportunity)
Now if you are attempting to run out the batsman a fielder wants to hit the stumps. A ball that bounces actually takes longer to get to the wickets since the bounce slows the ball and the trajectory is slightly further.
However a bouncing ball has more accuracy than one on the full. It is harder to hit the stumps on the full than a bouncing ball.
This decision is a split second decision.
Now as far as a returning the ball just to reset the game (no run out) a fielder should throw the ball on the full, and not hard either. A bouncing ball may make it more difficult for the wicketkeeper to catch and may risk overthrows.
As for damaging the ball Law 42 (FAIR AND UNFAIR PLAY) has a clause:
- The match ball - changing its condition
It is unfair for anyone to rub the ball on the ground for any reason, to interfere with any of the seams or the surface of the ball, to use any implement, or to take any other action whatsoever which is likely to alter the condition of the ball, except as permitted in (a) above.
Which means throwing the ball down at the wicket (which is much harder than the grass) could damage the ball. The umpire may warn the player (and captain) of such behaviour according to this rule.
