After all, the field was stacked with girls -- Anna Jensen, Anne Forsyth, Maggie Farrell -- who had tested themselves time and again over the indoor season at the distance.
Duffey, who had overcome a leg injury that hampered her 2015 cross country season, had just one race at the distance (1 mile) on her resume entering the field.
And while her time of 5:00.55 in the 1 mile at the Saginaw Valley State University meet on Feb. 11 paired well with her other competitors, it didn't quite translate to a winning performance. The 1-mile effort on Feb. 11 was U.S. No. 37 compared to three top 10 national times in the 1600m from Midland Dow's Jensen, Ann Arbor Pioneer's Forsyth, and Battle Creek Lakeview's Farrell.
But Duffey sure did crush those expectations.
The junior, a two-time third-place performer at the Michigan cross country championships, outkicked Jensen in the final 200 meters for a new personal best of 4:54.75 in the 1600m, giving her the nation's third-best time at the distance.
The MAC TV Network (credit above video) provides MITS Championship archived video free on their site here.
Her progression at the distance signaled at a big improvement, but by no means was the 4:54.75 expected on Sunday.
2017 - Feb. 26 - 4:54.75 - MITS Championships - Aquinas College
2016 - May 6 - 5:16.98 - Harold Arft Sterling Invitational - Sterling Heights
2016 - Apr. 14 - 5:36.61 - MAC Blue Fraser - Fraser High
2015 - May 1 - 5:14.21 - Harold Arft. Sterling Invitational - Sterling Heights
In December, Duffey told Michigan PrepZone's MLive.com, "Pretty much all I do now is school and running. I love it. It doesn't matter what else is going on in my life, running is something I do a lot of."
The expectations for Duffey heightened after her freshman cross country season, when she went 17:33.10 to finish third at Michigan's D1 championship.
But an injury limited her as a sophomore, halting her to a 14th place performance. As a junior, she didn't break 18 minutes but still finished third again at the state's cross country championship in 18:01.00.
Perhaps Duffey is now finally rounding back into form.
The 1600m only spells good fortune for the runner moving forward, possibly continuing at New Balance Nationals Indoor.