SURPRISE, Ariz. -- The Royals paved the way to open the season with a four-man rotation on Friday when they optioned Kris Bubic to Triple-A Omaha before a 4-4 tie with the Angels at Surprise Stadium. Because of multiple off-days in the early portion of the regular-season schedule, Kansas City isn’t going to need a fifth starter until April 16, two weeks into the season.

A combination of circumstance and performance left Bubic as the starter who will likely open the season at the alternate training site in Northwest Arkansas. The left-hander has struggled this spring (8.59 ERA in 7 1/3 innings).

“We knew going into this thing that we probably wouldn’t need that fifth starter for a while, so that would put us in a spot anyhow,” Royals manager Mike Matheny said. “We could have probably waited until the last day to let guys keep pitching, but we’re running out of those extended innings.”

Sending Bubic to the Minor League portion of camp allows him to work on the things he and the Royals have identified as weaknesses, including fastball command.

Bubic allowed three runs in 2 1/3 innings against the White Sox on Thursday, and despite having a sharp breaking ball and his signature changeup working for him, he had long at-bats and worked up to around a 30-pitch first inning.

The Royals are working to figure out if the problem is mechanical or Bubic’s approach. Bullpen sessions and batting practices on the back fields in Arizona are easier to find answers than against opposing batters late in Spring Training and early in the regular season.

“There’s this other guy that we both know is there,” Matheny said. “I’ve watched him have some of the best bullpen sessions that anybody in camp would have as far as fastball location, zip and three-pitch mix. I’ve seen him do it to where you watch and go, ‘Wow, that’s really impressive.’ That’s what I know is frustrating.

“You know sooner or later, it’s going to come together, but in the meanwhile, there are things that are getting in the way. When he finds that fastball location in games, it’s going to be really fun to watch this guy because he’s got some serious weapons.”

Matheny has been a strong advocate for Bubic since last spring, when the 23-year-old made a favorable impression with his approach and demeanor. And there’s little doubt that Bubic will be needed throughout the 162-game haul of this season, with the four-man rotation having the potential to grow to six depending on the schedule and workloads.

“I think that he should be absolutely in that conversation as a guy that can be in the rotation when that time is right,” Matheny said. “But the time needs to be right, and we need to get him right.”

While the Royals have not announced their Opening Day starter, the rotation to open the season appears to be Brad Keller, Brady Singer, Danny Duffy and Mike Minor. Right-handers Jakob Junis and Ervin Santana remain candidates to make the Opening Day roster in hybrid roles -- out of the bullpen for one or multiple innings, or as starters if needed.

Santana pitched out of the bullpen on Thursday, entering in the ninth with shorter notice, which was by design.

“We would love to see [Santana] prepare to be anything, whether that’s a guy that goes out and throws extended innings, that could potentially start a game for us, that could come in the middle for extended innings, or he could come in with one inning,” Matheny said. “A lot like what we’re talking with Jake as well, especially as we head out of the gate knowing that we need four guys, to have those other guys on the team, you’re going to have to serve a hybrid role until this kind of develops and defines itself what it looks like moving forward.”

Singer relies on fastball command

Singer took the next step toward the regular season with a five-inning outing against the Angels, with all three of his runs allowed coming on a three-run homer by Scott Schebler in the fourth inning. The right-hander’s slider didn’t have the depth it usually does, but Singer was able to rely heavily on his fastball location and movement to still keep hitters off-balance. He struck out four, walked one and hit one batter.

“Being able to go through any lineup with just using your fastball predominantly, that just shows you that it’s a special pitch, to be able to get the kind of swings that he’s getting,” Matheny said. “He got swing and miss, we saw rollovers, we saw jam shots. You have that kind of stuff, and limited to your arsenal, it just tells his maturity of understanding and wanting to be really good with one pitch, and also the fact that he can get away with that when not many people can.”

With one or two Cactus League starts left, Singer feels ready for the workload that will greet him come the regular season.

“I feel extremely strong,” Singer said. “I feel 100 percent prepared to keep going, let it go and go as far as I can. Just going to keep trying to sharpen everything.”

Quotable

“I told him he’s going to have a whole lot of fun in Kauffman [Stadium] if he keeps that stroke going.” -- Matheny, on Andrew Benintendi’s leadoff double in the fourth inning that landed on the warning track in left-center field.