What happens when a switch-hitter steps up to the plate against a switch-PITCHER? Well, your basic confusion and mayhem.
Staten Island Yankees pitcher Pat Venditte is able to pitch with either hand (quite well in fact). In last night's game against the Brooklyn Cyclones, Venditte faced the first two batters of the ninth as a right-handed pitcher. Then, switch-hitting Ralph Henriquez came to the plate to bat from the left side. Venditte switched his custom-made, six-finger glove to his right hand and prepared to pitch lefty. Henriquez then turned around to bat right-handed. The two players switched sides several times before umpires stepped in to discuss the issue.
After several minutes, they forced Henriquez to choose a side first; he chose to bat righty and struck out against the right-handed pitching Venditte. The rule in place states that the pitcher must declare which arm he will pitch with before the batter steps to the plate. He cannot change arms once the at-bat has begun.