Somebody has to get things going by delivering the ball which the batsman must keep from getting past him (if he misses and the bails are dislodged from the stumps on which they rest, he is out) and attempt to hit far enough away so he can score runs. Who is this pivotal member of the fielding team?

The bowler delivers the ball to the batsman, attempting to dismiss them by hitting the stumps (bowling them out) or induce mistakes for catches. If the batsman misses and the bails are dislodged, they are 'bowled.' This is cricket's fundamental adversarial relationship. 'Pitcher' is a baseball term; 'thrower' and 'bouncer' are not cricket positions.