Sentence:  Of all the cricket skills, good throwing is the one most readily appreciated by spectators, whether it be from the outfield or the infield. ... All throws must be "backed-up" by the nearest available fielder to prevent <WSD>overthrows</WSD> at both the bowler's and the wicket-keeper's ends. Nothing is more depressing than a fielding side giving away <WSD>overthrows</WSD> from bad throwing and backing-up. 
Meaning of the word marked with <WSD> tags:  A run scored by the batting side when a fielder throws the ball back to the infield, whence it continues to the opposite outfield.