Both players were out of options. The Royals said that Hayes cleared waivers and accepted an outright assignment to Triple-A Omaha rather than opting for free agency.
The two 29-year-old catchers waged a strong, camp-long battle for the right to back up regular backstop Salvador Perez. There's a catch to this catcher's job, though: He's not expected to play much, because Perez is projected to start between 140 to 150 games.
"They both did a great job, both kids fit the bill nicely," manager Ned Yost said. "The difference came down to a left-handed or a right-handed bat, and we opted to go with the left-handed bat.
"It was a coin flip. It was really tough. They both did a nice job behind the plate, both guys swung the bat really well."
Statistically, it couldn't have been more even. Oddly, going into the final spring game, both catchers had the same average, .306 (11-for-36). In 18 games, Kottaras had three doubles, six RBIs and a .468 on-base percentage. In 19 games, Hayes had a double, a triple, two homers, 10 RBIs and a .375 on-base percentage.
"It was a great spring with a lot of hard work, a lot of sweat, and I'm excited to get it going," Kottaras said.
Kottaras' left-handed bat balances Perez's right-handed swing.
"On days that Salvy does need days off, it'll probably be against tough right-handed guys, where you want to give him a break, so that's where the left-handed bat comes into play," Yost said. "If we pinch-run for Salvy late, I wanted a guy that could at least handle the pitching staff, and Kottaras did very nicely in that, as did Brett Hayes."
Kottaras came into the camp with the reputation of being a more offensively-geared catcher, with Hayes known as a catcher more defensively skilled. But, as time went by, Yost found both men proficient in both areas.
"We liked [Kottaras'] at-bats," Yost said. "There was a lot of no-panic at-bats all spring long, high on-base percentage, a kid that can hit the ball out of the ballpark. The rap on him coming in -- at least from what I was told -- was that he was a better offensive player than a defensive player, but that didn't prove to be so true for me.
"In Spring Training, he caught very well -- threw the ball, blocked the ball and received the ball very well. [He did] a nice job of game-calling, and we feel that he fits behind Sal."
Kottaras, from Scarborough, Ont., previously caught for Oakland, Milwaukee and Boston in back-up roles. In 249 Major League games, he has a .220 average with 24 home runs and 84 RBIs in 592 at-bats.
"I've been a backup my whole career up here, so it's one of those things where it's a constant battle to get better and learn," Kottaras said. "And I'm making small adjustments along the way, and the maturity factor definitely comes into play, too. The experience over the years and the players I've played with definitely help, too."
All of Hayes' experience came in 143 games with the Marlins over a four-year period from 2009-12. He has a .217 average, eight homers and 27 RBIs in 332 Major League at-bats.
Last year, with Perez missing about half the season, the Royals used four different catchers in starting assignments: Perez (74 games), Brayan Pena (46), Humberto Quintero (40) and Adam Moore (two). This year, Pena is with Detroit, Quintero is with Philadelphia and Moore is with Omaha.
The move gives the Royals this 25-man breakdown:
Starting pitchers: James Shields, Ervin Santana, Jeremy Guthrie, Wade Davis, Luis Mendoza.
Relief pitchers: Greg Holland (closer), Kelvin Herrera, Aaron Crow, Tim Collins, Luke Hochevar, Bruce Chen, J.C. Gutierrez
Catchers: Perez, Kottaras
Infielders: Eric Hosmer, Chris Getz, Alcides Escobar, Mike Moustakas, Elliot Johnson, Miguel Tejada
Outfielders: Alex Gordon, Lorenzo Cain, Jeff Francoeur, Jarrod Dyson
Designated hitter: Billy Butler
Pitchers Danny Duffy and Felipe Paulino will begin the season on the disabled list after having elbow surgery last year.