In games where the team pitches multiple players (staff day) and the starter does not meet the minimum requirements for a victory, the scorer is allowed to award the win to the pitcher he/she deemed most effective in the game. (It is a little known quirk of the game).
I believe this rule applies only if it is agreed upon by the head coaches prior to the start of a game. I've seen many box scores early in a season where Johnny Wholestaff pitches -- one inning at a time -- and sometimes the pitcher of record is the starter, who worked an inning, his team got a lead, and the rest of the staff held the lead for the balance of the game. A pitcher can pick up a win after a one-two-three first and then sit for the next eight innings! The downside is that a pitcher can give up an unearned run in the first, be taken out, and eventually get tagged with the loss.
When I am scoring a game and the opponents start shuttling pitchers in every inning or two, I check with our coach to see if that rule is in force.
WINNING PITCHERhttp://www.ncaapublications.com/productdownloads/BA09.pdfThe scorer shall have sole authority to make all decisions involving judgment
Winning and Losing Pitchers
SECTION 25. a. For all games of eight or more innings, a starting pitcher
must pitch at least five complete innings to receive credit as the winning pitcher.
b. If the starting pitcher does not pitch enough innings, the win is credited to a relief pitcher in the following manner:
(1) The winning relief pitcher shall be the one who is the pitcher of
record when his team goes ahead and remains ahead throughout the
remainder of the game.
(2) By pre-arrangement, if three or more pitchers are to be used, the
pitcher of record shall be considered the winning pitcher.
Note: The pitcher of record shall be the one who is in the game at the time the winning team gains the lead, provided that the lead never is relinquished, or the one who is charged with the runs by which the opposing team takes the lead, provided that the lead never is relinquished.