Shortly after the New Orleans Zephyrs dropped a series finale to the Albuquerque Isotopes on Sunday, Jennings learned that he was headed to Miami to join the Marlins in the big leagues. He made his debut in Monday's game against the D-backs, tossing a scoreless sixth inning.
"We had a day game yesterday and I was in the weight room lifting," Jennings said of when he first began suspecting that he may have earned a call to the Majors. "A couple of funny things happened, like they wouldn't give me my meal money for the road trip. Then somebody said the manager [Ron Hassey] was looking for me, but he was in the shower, so I was just wandering around the clubhouse waiting.
"I saw somebody tweeted something that I saw about me coming up, so I went and found the manager. Then about as casually as you could possibly be -- and this is a guy who spent a lot of time in the big leagues and caught two perfect games -- he just says, 'Hey, you're going to the big leagues.' It was kind of a cool way to find out."
Outfielder Bryan Petersen joined Jennings on the trip to Miami, and he was happy to see his friend finally realize the dream of making it to the Majors.
"This is my sixth time [being called up]," Petersen said. "It's cool and I'm super excited to be here, but I was more mellow about it when I heard. You could see how excited he was, calling people up and letting them know. I was super happy for him. It's awesome. He'll do a good job."
Despite the Marlins taking the loss on Monday, Jennings did a good job in his first big league opportunity. The left-hander retired three of the four batters he faced, with his one blemish a two-out walk to infielder Ryan Roberts.
"It was exciting, nerve-wrecking, everything you expect it to be," Jennings said of his debut. "It would've been nicer if we came out with a win, but it's good to get that first one out of the way."
Just getting to the ballpark in time for the game was a bit challenging for Jennings, as he and Petersen had a wild trip to join the Marlins before Monday's scheduled first pitch at 12:40 p.m. ET.
"The best word to describe this is 'chaos,'" Jennings said. "We got about three hours' notice, packed up our stuff at the ballpark, rushed home as quickly as I could to pack a suitcase and go to the airport. We got in late last night, and there's a quick turnaround with the early game today. I haven't really had a chance to catch my breath yet."
Opposing hitters have not caught their breath very often against Jennings in Triple-A this season. The left-hander has a 2.08 ERA with 10 strikeouts over 8 2/3 innings with the Zephyrs.
Jennings will replace Mike Dunn as the second left-hander out of the Marlins' bullpen. Dunn, who has a 9.53 ERA in 5 2/3 innings this year, was sent to New Orleans after giving up three runs over two-thirds of an inning on Sunday.
"I understand what is expected of me," Jennings said. "Being a lefty out of the bullpen, I'm probably going to see a majority of left-handed hitters, but I am ready for whatever situation they put me in."
Jennings has had an interesting road to the Majors. Once a promising prospect in the Marlins' organization, Jennings' luster began to fade after he was suspended 50 games in 2010 for the use of performance-enhancing drugs.
Since then, he has proved himself worthy of a big league callup, and now he is excited about finally making it to where he has always wanted to be.
"It feels like a big weight has been lifted off my shoulders," Jennings said. "Ever since that suspension, a lot of people said, 'Maybe it's not going to happen' or 'When are you going to get called up?' Nobody knows that. It's all up to how things play out. It just feels like I can take a deep breath now and a big weight is off my shoulders now that I finally made it up here."