The moves, coming four days after the completion of the team's minicamp in Las Vegas, come two weeks before the opening of training camp in New York, beginning Aug. 9.
More cuts are ahead, as the U.S. federation must submit a 12-man roster Aug. 26 -- two days before the Americans open pool play against Croatia in Istanbul, Turkey, at the 2010 FIBA World Championship.
The cuts left the team with six guards (Derrick Rose, Chauncey Billups, Russell Westbrook, Rajon Rondo, Stephen Curry and Eric Gordon); four wingmen (Kevin Durant, Andre Iguodala, Rudy Gay and Danny Granger); three power forwards (Lamar Odom, Kevin Love and Jeff Green); and two centers (Tyson Chandler and Brook Lopez).
"Certain players were told that they are right on the bubble and New York is important to them in terms of making the final roster," USA Basketball chairman Jerry Colangelo said.
Evans, the NBA Rookie of the Year last season for the Sacramento Kings, was the most likely to be cut from the roster after missing the final two days of practice and the team's public intrasquad scrimmage Saturday night.
Wallace played poorly in the scrimmage -- no rebounds, no steals, 0-for-4 on 3-pointers in 12½ minutes of playing time -- and his deletion from the roster reduced some of the glut at the wing positions.
Mayo, after what was described by team insiders as a sluggish four days of practice, played well in the scrimmage with 18 points and seven rebounds, making 3 of 6 3-pointers.
McGee brought a unique skill set to the team with his ability to play above the rim, block shots and convert around the basket, but he did not survive the cut.
"We really did have some difficult decisions," Colangelo said, adding that the team may head to Europe with 13 or 14 players for a stretch of exhibition games in Madrid on Aug. 21-22 (against Lithuania and Spain) and Athens (against Greece) on Aug. 25.
Team USA opens its exhibition schedule with a game against France Aug. 15 at Madison Square Garden in New York.
Chris Sheridan is a senior NBA writer for ESPN.com.