The former second-rounder threw seven innings of two-hit ball, striking out six and walking two to record his first career shutout in a 5-0 victory over the St. Lucie Mets on Thursday.
Just two hours earlier, the Florida Marlins' Class A Advanced affiliate had wrapped up a another two-hitter, a 2-0 win over the Mets to complete Wednesday's game that had been suspended because of rain.
The complete-game shutout was the Hammerheads' second of the year and the first since Matt Montgomery threw a nine-inning shutout in a 6-0 win over Fort Myers on June 14.
"It helps to have familiarity playing a team," said Rasmussen, selected by the Marlins 73rd overall in the 2010 Draft. "We played them in Spring Training and we've played them frequently in the season. This was my second start against them, and they also fielded the exact same lineup in the second game of the doubleheader as they did in the first.
"I write down what works well against hitters, what doesn't work and what I need to work on. If there's a hitter that I have success against, I make a note of it so I know what to throw them when I face them later on."
After the Hammerheads wrapped up the final four innings carried over from Wednesday's game, Rasmussen (9-9) followed his teammates' lead in stifling the St. Lucie lineup.
The UCLA product was perfect through the first three innings before allowing a single to Pedro Zapata to lead off the fourth. But Rasmussen struck out Cesar Puello and Wilmer Flores grounded into an inning-ending double play.
The California native loaded the bases in the fifth with consecutive two-out walks and Francisco Pena's single to left field, but he worked out of trouble by getting Rylan Sandoval to hit a weak ground ball to shortstop Jeff Dominguez to keep the shutout alive. He then set down the side in order in the sixth and seventh to complete his shutout bid.
"I felt really good. A lot of my pitches were going where I wanted them and the catcher [Sharif Othman] and I were on the same page," said Rasmussen, who threw 91 pitches and took just one hour and 54 minutes to complete the shutout. "That helped give me quick innings and go deep into the game. I had a little trouble in the fifth inning, but I had a quick sixth which kept my pitch count down and gave me some wiggle room in the seventh.
"In my mind, I know this was just a seven-inning doubleheader. It would have been more exciting if it was nine innings, but it was definitely still rewarding."
The victory helped Rasmussen lower his ERA to 3.69. He has not given up an earned run in seven of his 23 Florida State League outings, and he has allowed just one unearned run on four hits over his last two appearances.
On July 30, the left-hander struck out a career-high eight batters over seven two-hit innings in a 3-2 loss to the Daytona Cubs, but he did not factor in the decision.
"The last two starts have been the best of my career, but I would say this one is No. 1 just because we got the win. Both Daytona and St. Lucie won the first half of their respective divisions, and even though some players have been called up, it's still nice to have success against quality teams."
On Wednesday, the Hammerheads and Mets were scheduled to play a doubleheader to make up for a game rained out June 25, but the second game was suspended midway through the third.
Jupiter's Jose Rosario had allowed two hits and struck out five when the game was stopped. John Omahen replaced Rosario when the game resumed, tossing three hitless innings before turning the ball over to Alejandro Ramos, who struck out the side in the seventh to seal the victory.
"Rosario has been unbelievable. He can do whatever you need him to do," Rasmussen said. "He could have pitched four, five, six innings yesterday if not for the rain.
"Omahen is fun to watch. He was a shortstop in college and he knows how hard it is to hit when you're behind in the count, so he goes right after hitters. And Ramos is unbelievable as a closer. It's so nice to have someone like him to give the ball to."
The shutouts were Jupiter's ninth and 10th of the year, and the first back-to-back shutouts since a 1-0 win over Bradenton on April 19 and a 5-0 victory in Palm Beach the following day.