Tseng arrived in Chicago on Wednesday, thinking he was going to be honored pregame on Friday as the Cubs' Minor League Pitcher of the Year. He'd been throwing at the team's complex in Arizona, but didn't know he'd be making his debut until he met with manager Joe Maddon on Wednesday.
"I was thinking I was just here [in Chicago] to receive the award," said Tseng, the Cubs' No. 13 prospect. "When [Maddon] told me I was going to pitch, I was kind of nervous."
The Taiwanese right-hander went three innings on Thursday night against the Mets, who scored five runs off him. The Cubs rallied to win, 14-6, completing a sweep of the series.
"I like the kid a lot, I really do," Maddon said. "Obviously, a little nervous. [He and Davis] had that 'never let them see you sweat' moment, and they did. Jen-Ho showed me great carry on his fastball and I loved his changeup. It was good."
Tseng's first pitch to Mets leadoff batter Jose Reyes was a called strike, and he got Reyes swinging at the next pitch. But Tseng then threw four straight balls, and the last one went behind Reyes' back.
"I was a little bit nervous on the first pitch, and then I felt more comfortable," Tseng said. "After 3-2 [to Reyes], I threw a cutter that went behind the batter, and after that I became more nervous."
"It was an awkward first night for him," Maddon said. "Moving forward, I like him. I've seen very successful pitchers throw like him."
However, Tseng most likely won't get another start the rest of the season. Jake Arrieta, who has been nursing a sore right hamstring, will likely return to the rotation. Maddon said nothing had been determined yet.
"I really believe that the next time out, you'll see more pinpoint command out of him," Maddon said of Tseng. "I can see this guy putting the ball where he wants to."
"Just breathe. Have fun," Rizzo said of his message to the young pitcher. "Until you go out there and do it, that's when you hit the biggest learning curve. I thought he did a really good job controlling his emotions. He had a few hiccups there, but he threw strikes and punched guys out and looked pretty good."
There were some hiccups in the first. After Reyes walked, Brandon Nimmo reached on an error by Tseng, who couldn't get his glove on a throw from Rizzo and fell at first base. Asdrubal Cabrera hit a sacrifice fly and Tseng then hit Dominic Smith with a pitch. But the pitcher, the first from Taiwan to play for the Cubs, struck out the next two batters to end the inning.
"I really don't think he pitched that bad," said Davis, who caught all but one of Tseng's starts at Triple-A Iowa. "He struck out six guys over three innings."
Tseng did collect some souvenirs, including the ball from his first big league strikeout. He also got his first Major League RBI with a run-scoring groundout in the second that tied the game at 3.
"I can do better than that," Tseng said.
Tseng was 13-4 at Double-A Tennessee and Iowa combined. He's got potential. What did he think of his first time pitching at Wrigley Field?
"I didn't think pitching in the big leagues would come so fast," Tseng said.
Carrie Muskat has covered the Cubs since 1987, and for MLB.com since 2001. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.