FORT MYERS, FLA. – The Twins might have discovered a way to avoid deciding between Kyle Gibson and Scott Diamond for the final spot in the rotation.

Because rain washed out Monday's game and made the minor league fields unplayable Tuesday, the Twins added Mike Pelfrey to the schedule against the Orioles. And Pelfrey, Diamond and Gibson each threw three splendid innings as the Twins beat Baltimore 4-1.

"We're going to throw three starters every day the rest of the year," Twins manager Ron Gardenhire said. "I told [Phil] Hughes, 'You're going every three days.' I told [closer Glen] Perkins, 'Take a hike, we don't need you anymore.' "

Alas, it was in jest, and the Twins aren't ready to officially announce their No. 5 starter yet. All signs point to Gibson being their man. He didn't disappoint Tuesday, throwing three shutout innings on two hits with one strikeout to lower his spring training ERA to 2.20.

Diamond entered his outing with a 5.79 ERA and gave up one earned run over his three innings, on Steve Pearce's sacrifice fly in the fifth. It was his most effective outing of spring training, but it probably will not be enough.

Since he is out of options, Diamond would have to clear waivers in order to be sent to the minors. He is coming off a 6-13 season, but some club in search of pitching could claim him in the hope the lefty will rediscover the form that allowed him to go 12-9 with a 3.54 ERA as a rookie in 2012. The Twins could also shop him around in hopes of trading him.

Gardenhire praised Diamond for how he pitched Tuesday but added that he hoped Diamond got a chance with another organization if things don't work out with the Twins.

"I don't want to see him in the minor leagues pitching somewhere," Gardenhire said. "I don't think that's fair to him. I think he should be in the big leagues. It's totally up to him and his performances.

"I think he's pitched well enough in this camp and we'll see how we finish off here. We've got a number of issues and all those things. We've got tough decisions and we will see how they turn out and where it ends up."

Gibson has been steady all spring, which some moments of nastiness. At 26, the Twins believe it's time to see what their first-round draft pick from 2009 can do in a full big-league season.

"I've been pretty satisfied," Gibson said. "I worked on the things that I wanted to work on, made the adjustments I wanted to make. I've been more aggressive, I've been making more quality pitches in the zone and not working from behind. I think the hits I gave up today were from behind in the count."

Gibson is expected to join a rotation that includes Ricky Nolasco, Kevin Correia, Phil Hughes and Pelfrey. Pelfrey got things rolling Tuesday with three shutout innings during which he struck out four.

Gardenhire said the final roster decisions — they need to cut four players — will be settled by Friday. But he sounded as if Gibson has positioned himself for a plane ride to Chicago for Opening Day.

"Gibby has been great all through camp," Gardenhire said. "I haven't seen too many problems with the young man. He's got a great angle going. The biggest thing for him is not yanking balls, not overthrowing. You see him overcook a slider once in a while but other than that the ball is coming out of his hand really nice. He's done everything you're supposed to do here."