Umpires working Creighton’s games have to dust off seldom-used rules regarding switch-pitchers. Like everyone else, Venditte gets only eight warm-up pitches upon entering a game and five before any inning, whether he chooses to throw left-handed or right-handed, and may not warm up again if he changes arms midinning.

A switch-pitcher facing a switch-hitter could make a fine Abbott and Costello routine. Against Nebraska last year, a switch-hitter came to the plate right-handed, prompting Venditte to switch to his right arm, which caused the batter to move to the left-hand batter’s box, with Venditte switching his arm again. Umpires ultimately restored order, applying the rule (the same as that in the majors) that a pitcher must declare which arm he will use before throwing his first pitch and cannot change before the at-bat ends.

“Eventually, after 10 or 15 minutes, they got it figured out,” Venditte said with a smile.

Venditte’s customized Louisville Slugger glove is as distinctive as its owner: four fingers are flanked by two thumbs, perfectly symmetrical, so that he can slip it on either hand with ease. It allows him to change throwing arms so seamlessly during warmups — one second No. 27 is throwing left-handed, the next right-handed — that many unaware fans and opponents do double-takes.

“The first time you see him, it’s definitely a distraction,” said Northern Iowa shortstop Brandon Douglas, who struck out (right-handed) against Venditte last Friday. “On the bus ride to games people talk, ‘You should see this guy. It’s pretty neat.’ ”

Until teams actually face him, that is. Creighton’s coach, Ed Servais, initially resisted using Venditte both ways because, he said, “I am a traditionalist when it comes to baseball, and I didn’t want it to become a circus.” But Venditte proved his ability last season, when he used both arms in 22 games and struck out batters each way in 12 of them.

Image Pat Vendittes name split a lineup card. Credit... Chris Machian for The New York Times

The Bluejays use Venditte as a long reliever so that he can be deployed at any point in any game. In the Northern Iowa game last Friday, for example, Venditte quelled a third-inning rally and then, facing a lineup that alternated its lefty and righty hitters, calmly switched throwing arms 10 times in the next five innings and allowed no runs and only one single. (Pitch limits are looser with Venditte because he shares the workload between his arms.)