May, a catcher for Triple-A Omaha, appeared in 12 games for the Royals last season, hitting .189. In 25 games for the Storm Chasers this season, May was hitting .176 with a .263 on-base percentage and .329 slugging percentage. May had three home runs and 13 RBIs for the year.
Acquired from the Los Angeles Dodgers in the Scott Podsednik trade, May and Brayan Pena were going to be the Royals' catchers this season. But when the Texas Rangers made catcher Matt Treanor available, the Royals acquired him, sending May to Omaha.
Pizziconi, a 19-year-old signee out of Italy, had a 2.57 ERA in 49 innings pitched for the Missoula Osprey and Yakima Bears in 2010. The Royals assigned him to Rookie level Idaho Falls.
Catcher Cody Clark was reinstated from the seven-day disabled list to fill the Omaha roster spot.