"I acted like a regular student," Horst said.
When they saw him throw, the school's baseball players started quizzing Horst. "Have you ever played baseball?" they asked. "Oh man, we could use some lefties," they said.
"Too old," Horst told them. "I'm just taking a couple of classes."
The 27-year-old Horst fooled everyone in 2012. He was acquired in an offseason trade for Wilson Valdez and appeared in the Phillies clubhouse one day last June when the Chad Qualls experiment ended.
All Horst did was throw strikes and take the ball whenever asked. He pitched to a 1.15 ERA in 311/3 innings and filled every role. He quickly became a trusted arm to Phillies officials who extolled his attitude.
The results had not extended to this spring until Sunday. Horst pounded the zone and struck out two of the three Astros he faced. The Phillies recorded their second Grapefruit League one-hitter of the spring in a 7-1 win over Houston.
Before Sunday, Horst had permitted eight runs on 10 hits and three walks in five Grapefruit League innings. Six of those runs were scored in one forgettable outing with blustery winds in Sarasota.
Pitching coach Rich Dubee said there has to be some benefit of the doubt when evaluating Horst's spring. Just about every Phillies official has echoed that.
"I have confidence in Horst because he pitched so well for us last year," Phillies general manager Ruben Amaro Jr. said. "He has to have a little bit of an edge over some of the other guys."
The Phillies have three bullpen openings and have prioritized relievers who can throw multiple innings. They would also prefer a second lefty to Antonio Bastardo. Horst fits both categories.
"He's a great professional," Dubee said. "He goes about his business, does his work. He's durable. He's resilient. He can pitch back-to-back days, in multiple innings. He was a big-time strike thrower for us last year."
Or, as Charlie Manuel described Horst, "He's gutty."
"I love the fact that Charlie and Dubee know they can put me into any situation," Horst said. "Hopefully they feel comfortable doing so. I definitely like coming in and throwing multiple innings. Having a guy to eat innings is huge. I take pride in that."
Adjustments are required for Horst, a relative unknown in 2012, to continue success. The league has seen him. Lefthanded hitters staggered to only one extra-base hit in 52 plate appearances against Horst.
They will know what is coming in 2013. To his advantage, Horst throws three pitches.
"Sometimes you can get away with having the same pitches but it's just your approach is a little different," Horst said. "Maybe locating certain pitches in different spots at different counts. Hitters will watch a lot of tape trying to pick up tendencies for pitches and counts.
"I look forward to that challenge."
Dubee said Horst is traditionally a slow starter. Horst arrived to Florida two weeks before camp started. That was the first time he threw outside, and he didn't need to pretend to be a college student.
"I'm fortunate enough," Horst said. "Where I live, nobody really knows me."
Darin Ruf's day was prematurely ended in the sixth inning Sunday when former Phillies prospect Jarred Cosart drilled him on the arm with a pitch. Ruf, who did not appear to be in overwhelming pain as he walked to the Phillies clubhouse, was struck above his left triceps. While icing it, he said through a team spokesman that he felt fine. . . . Cole Hamels allowed two base runners in five innings but was not happy about his mechanics and command. Hamels has three more spring starts to make corrections. . . . Domonic Brown had his first day of rest this spring. The entire team is off Monday. . . . The Phillies reassigned catcher Cameron Rupp to minor-league camp.
Contact Matt Gelb at email@example.com. Follow @magelb on Twitter.