From BR Bullpen
- An assist shall be credited to each fielder who throws or deflects a batted or thrown ball in such a way that a putout results, or would have resulted except for a subsequent error by any fielder. Only one assist and no more shall be credited to each fielder who throws or deflects the ball in a run down play which results in a putout, or would have resulted in a putout, except for a subsequent error. NOTE: Mere ineffective contact with the ball shall not be considered an assist. "Deflect" shall mean to slow down or change the direction of the ball and thereby effectively assist in putting out a batter or runner.
One important exception to the putout rule is that a legal pitch does not count as a throw under the rules. Thus the pitcher does not receive an assist on a strikeout or caught stealing unless he touches the ball again after the pitch.