Oh navigated through a scoreless seventh, issuing two walks before closing the frame with consecutive strikeouts of David Freese and Starling Marte. He exited with a keepsake ball from the appearance.
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"The Major League debut was great," Oh said, speaking through translator Eugene Koo. "The fact that I let the first hitter on with a walk was a little disappointing, but overall it was OK."
While assimilating to a new culture, familiarizing himself with new teammates and gauging new competition, Oh pieced together a strong Grapefruit League showing. It cemented his place as a late-inning option in a bullpen that will be without Jordan Walden for the foreseeable future.
Even though Oh earned his "Final Boss" nickname in Asia because of his dominance as a closer, the 33-year-old right-hander welcomes the role of serving as a bridge to Cardinals closer Trevor Rosenthal.
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"Focusing on what I'm doing well or what I have done well in the past is the focus for me now," Oh said. "From a team standpoint, they didn't pick up someone who is a rookie or very young. They brought in someone who is already experienced."
Koo, who was jokingly described as a "forced best friend" in spring, made his debut on Sunday, as well, when he sprinted to the mound to help interpret during a visit from catcher Yadier Molina.
As for how that went?
"That was great," Koo laughed. "I'm glad I didn't trip."
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, follow her on Twitter @LangoschMLB, like her Facebook page Jenifer Langosch for Cardinals.com and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.