"I called him back," Armstrong said with a laugh. "And he said, 'So, are you ready to go to Cleveland?'"
Armstrong, the Tribe's No. 27 prospect, officially joined the Indians on Saturday and worked a clean ninth inning for his Major League debut in the Tribe's 17-4 rout over the Twins. The hard-throwing right-hander struck out two, induced a game-ending flyout and fired eight of his 10 pitches for strikes.
It was a brief look into Armstrong's potential, but Indians manager Terry Francona was impressed.
"Oh, man. I thought his stuff was really kind of as advertised," Francona said. "The guys said that he was coming kind of feeling good about himself. You could see that. Shoot, if I threw like that, I'd feel good about myself, too."
According to the PITCHf/x data, the 24-year-old Armstrong averaged 97.2 mph with his fastball (topping out at 98.6 mph) and 93.9 mph with his slider. Minnesota's Aaron Hicks and Chris Herrmann were the young reliever's first two career strikeout victims, and Eduardo Escobar flew out to center field to seal Cleveland's win.
Finishing games was one of Armstrong's responsibilities at Triple-A, where he spun a 2.25 ERA with 69 strikeouts and 14 saves in 40 appearances (44 innings).
Francona said the ninth inning of Saturday's blowout win was the "perfect" way to have a young pitcher get his first taste of the big leagues.
"I couldn't really feel my feet when I went out there," Armstrong said. "It felt a little different. It's like [bullpen coach Jason Bere] said out there in the 'pen. He said, 'It's the same game -- just a lot more people. Don't change anything.' That's the best thing that he could've told me, and that's all I did, was try to focus on the strike zone."
And when the bullpen phone rings, Armstrong does not plan on missing the call.
Jordan Bastian is a reporter for MLB.com. Read his blog, Major League Bastian, follow him on Twitter @MLBastian and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.