* Kansas City Royals -- Signed Jeffrey Leonard, designated hitter, to a contract with Omaha of the American Association.
* Seattle Mariners -- Signed Tommy Adams, outfielder.
* Toronto Blue Jays -- Placed Ken Dayley, pitcher, on the 15-day disabled list. Activated Kelly Gruber, third baseman, from the 15-day disabled list.
* New York Mets -- Recalled Julio Valera, pitcher, from Tidewater of the International League. Sent Chris Donnels, infielder, to Tidewater.
* Detroit Pistons -- Agreed to terms with Chuck Daly, coach, on a contract extension through the 1991-92 season.
United States Basketball League
* Atlanta Eagles -- Activated Carlos Funchess, guard, from the taxi squad. Placed Anthony Jones, guard, on the taxi squad. Moved Mike Smith, center, from injured reserve to the taxi squad and Orlando Graham, center, from the taxi squad to injured reserve.
National Football League
* Buffalo Bills -- Signed Bjorn Nittmo, placekicker; Chris Mohr, punter; Ron Sancho, linebacker; and John Garrett, wide receiver.