Gil Meche, Brian Bannister and Davies are virtual locks for the rotation. However, the final two spots can be filled by a variety of pitchers.
Nunez, who was thrust into emergency duty in mid-July at Fenway Park, has a 1.80 ERA in four appearances (three starts).
Projected as a reliever, Nunez could be viewed as a long-term option for the rotation.
"If Nunez keeps pitching the way he is pitching, that doesn't become a choice," Bell said. "You need to keep him in the rotation."
Jorge De La Rosa, John Thomson and Brandon Duckworth are set to return off the disabled list in the next few weeks and could compete with Odalis Perez (5.87 ERA) for a spot.
De La Rosa is set to make another bullpen appearance Monday and will make at least one rehab start. Thomson, who allowed five runs in two innings for Double-A Wichita on Saturday, is another option to start.
Duckworth (oblique strain) is scheduled to throw for Triple-A Omaha on Wednesday, while Thomson will pitch for Wichita on Thursday. Both likely won't return by Sept. 1, but can be used as starters if necessary.
"Couple weeks ago, we had no options," Bell said. "Duckworth comes back, Thomson comes back, De La Rosa comes back. We are going to have some decisions and some tough decisions."
Top prospects Billy Buckner (8-7, 4.10 ERA) and Matt Wright (8-3, 3.86 ERA) could also present further options when rosters expand on Sept. 1.
"I don't know," Bell said. "[General manager] Dayton [Moore] and I have talked a couple of times about what we are going to do in September, but nothing really official. I don't really know. It just kind of depends on the number of innings that are available, the options -- starting service time is always an issue. I really don't know for sure."
Steals unlikely: Entering Saturday night, the Royals were tied for 12th in the American League in steals (53) and tied for last in stolen base percentage (65 percent). However, the Royals stole five bases off starter Dustin McGowan and catcher Gregg Zaun on Saturday. It was the most steals in a game for KC since June 19, 2004.
Zaun has the worst caught-stealing rate of any American League catcher with at least 50 games caught this season, and historically doesn't have a strong arm. However, Bell said the team stole the bases of McGowan's slow delivery.
"It has everything to do with the pitcher," Bell said. "Very seldom anymore do you steal on a catcher. It's usually young guys like guys last night who are not really quick to the plate. That's basically the bottom line. Zaun does a good job of getting rid of it and getting it down there."
However, Bell said the Royals won't start stealing more -- unless they have a similar situation to Saturday.
"We really don't have a lot of speed," Bell said. "It really depends on who is pitching more than anything else. We can't push the envelope there. We would just be running into outs."
Lefty-heavy lineup: Bell stacked his lineup with six left-handed starters for Saturday's game. He usually likes a left-right-left-right order through his lineup, but wanted to give the left-handed-hitting Jason Smith a start.
Smith batted seventh -- one of four straight left-handers for KC.
"I wanted to play Smitty and there is no other way," Bell said. "I toyed around with a couple different options, but that when seemed to be make the most sense as we moved into the sixth, seventh and eighth innings as far as pitch-hitting and things like that."
Sunday night game rare: The Royals had an oddity Sunday -- it was their first Sunday night game of the season. Because of the Kansas City weather and the wraparound series that ends Monday, KC played the game at night.
"It's a bit peculiar," Bell said. "We used to have Sunday night games in Texas, but I don't think we have had one here since I have been here. Or anywhere really, unless you are on a nationally televised game."
O'Neil seat: Dave Benyo from Lee's Summit, Mo., is sitting in Buck's seat for Sunday's game. Benyo, a teacher for more than 15 years, fought a battle with cancer that left him with severe paralysis. He still taught and finished with 31 years of service.
Royals' Rundown: Triple-A Omaha lost, 7-5, to Memphis. Luke Hochevar, the No. 1 overall pick in the 2006 First-Year Player Draft, cruised for six innings, but had a rocky seventh. He finished with four earned runs in 6 2/3 innings. ... Julio Pimental scattered three hits in five shutout innings, but Class A Wilmington lost, 4-1. Mario Lisson extended his hitting streak to 10 games with a single. ... Peter Hodge Nielsen, the team's fourth-round pick in the 2007 Draft, allowed a career-high six runs in three innings in Rookie League Arizona's 10-1 loss to the Arizona Giants.
Coming up: Perez (6-11, 5.87 ERA) faces rookie Jesse Litsch (4-4, 3.64 ERA) in the final game of the series Monday night at Kauffman Stadium. First pitch is set for 7:10 p.m. CT.