Gonzalez left his previous start due to a groin strain and Showalter said Britton and Belfiore were also needed insurance in case Gonzalez re-aggravated the injury early in the game.
"I don't care how many sprints, stretches, side work he's done," Showalter said. "There's a different intensity in a game. You can't imitate getting off the mound and getting a ground ball. We've tried everything, so you better cover yourself."
No Wada for Orioles
The Orioles also could have added left-hander Tsuyoshi Wada, who has not thrown a major league pitch since being signed to a two-year, $8.14 million deal in January 2012, but the club decided to keep him in Sarasota.
Wada, 32, missed all of last season with an elbow ligament tear that required surgery. The pitcher rehabbed this year in Sarasota and at Norfolk, where he was 5-6 with a 4.03 ERA in 19 starts.
"He was an option," Showalter said. "We felt like these guys (Britton and Belfiore) have both been here this year and were a little more ready to cover us better."
The club has a $5 million option for Wada next year, but it appears that his Orioles career may have ended before it started.
Here are some of the eye-popping numbers from Friday's 5-4 loss to the Rays in 18 innings: The teams combined to use a major-league record 21 pitchers. … They combined for 593 pitches; 301 by the Rays. … There were 144 combined plate appearances. … The Rays had never played in a six-hour game or won one after 14 innings. Their longest game, innings-wise, had been 16, done twice. … It was the second-longest game this season, 12 minutes shorter than the Arizona at Philadelphia game on Aug. 24 that also lasted 18 innings. … The Orioles are 3-2-1 in games that last at least 18 innings in their history. Their last 18-inning game was Sept. 18, 2012. … The Orioles' previous longest game, time-wise, was six hours and 15 minutes on July 2, 2004 at Philadelphia. … The only big league game in Orioles' modern-day franchise history that was longer than Friday's, innings-wise, was a 7-5 victory over the Washington Senators at Memorial Stadium on June 4, 1967 that lasted 19 innings. Andy Etchebarren won the game with a two-run homer after twice failing to lay down a sacrifice bunt.