Ace right-hander Ervin Santana (6-1, 1.50 ERA) was set to start the Wednesday home game against the Colorado Rockies, and Molitor didn't want to lose Santana to a short outing if the game was postponed after starting.
Minnesota already had an opening in the rotation for Saturday, with minor league left-hander Adalberto Mejia a possibility to take that spot. Following the postponement, Minnesota will stick with Santana and Thursday's scheduled pitcher, Jose Berrios, for the doubleheader, potentially leaving another open spot next week.
"The wheels are spinning," Molitor said after the postponement was announced Wednesday following a short delay. "We've got to try to map out the pitching here over the next month. We need a sixth starter. We've gone with three and now we need a sixth."
Rain arrived just about game time on Wednesday to cause a delay. A bad forecast led to the postponement about 30 minutes later.
Wednesday's scheduled starters, Santana and Colorado right-hander German Marquez (1-2, 4.88) will start the Thursday afternoon game. Berrios (1-0, 1.17) and right-hander Tyler Chatwood (3-5, 5.25) were the scheduled starters for the series-ending matinee, but they will take the mound in the makeup affair Thursday night.
"The optimism never panned out," Molitor said after the postponement. "It looks bad out there. They thought it was going to be dry until 8 o'clock."
Molitor said the team would recall right-handed reliever Drew Rucinski from Triple-A Rochester as the 26th player for the doubleheader. Colorado didn't announce its extra player.
Strong pitching has helped Rockies post the third-most road wins in the National League despite playing the second-fewest road games in the majors. Colorado improved to 12-5 on the road with a 7-3 win at Minnesota on Tuesday.
The Rockies' 3.21 road ERA is the second-lowest mark in the majors and the lowest in the NL.
Marquez, one of three rookie starters in the rotation, is coming off eight scoreless innings against the Chicago Cubs in his last outing. He will be facing the Twins for the first time in his career.
Chatwood has performed better on the road. He owns a 3.98 ERA in three roads starts this season and a 6.18 ERA in five starts at Coors Field.
Chatwood is 0-1 with an 8.68 ERA in two career starts against Minnesota, but both came back in 2011.
Santana has a 2-1 record and a 6.31 ERA in four career starts vs. Colorado, while Berrios will be making his first appearance against the Rockies.
Colorado manager Bud Black knows Santana well from their time together with the Los Angeles Angels. Black was the Angels' pitching coach for Santana's first two major league seasons.
"What's impressive is the really low hits per innings pitched," Black said. "You just don't see that ratio in today's game unless you really are making pitches."
Black has been impressed with Santana's start, which had him second in the AL in ERA and wins entering the Wednesday's action. Santana also held the league's lowest opponent's batting average. Black doesn't feel Santana's repertoire has changed much over the years, though.
"I think it's just experience and he'll probably be the first to tell you," Black said Wednesday. "Delivery is pretty much the same. The body's the same. I think the head's different; and not that it was a bad head earlier, but just younger and inexperienced. Now he's experienced, calm, confident."
If only Molitor and the Twins had others like Santana to fill the empty spots in the rotation.