Tinkle, in his first season as head coach of the Beavers, does not have any seniors on the team.
He started four players who made the team in an open tryout Oct. 4 and one who was a practice player last season under former coach Craig Robinson.
"Some people might call me crazy and maybe I am," Tinkle said, "but it was something our guys deserved."
Those players might not be on the team next season due to a strong recruiting class.
"I was thinking about having no seniors to celebrate what would normally be "Senior Night" and I wanted to honor something for this team," Tinkle told ESPN.com in a text message. "It hit me right away: Honor the walk-ons from Oregon that have been such a big part of our season.
"Knowing what I now know, I'd do it all again. One of my proudest moments as a coach!"
Oregon State pulled to within one with 34 seconds left after a Malcolm Duvivier layup, but Oregon made six free throws in the final 30 seconds to secure the win. The Beavers committed two costly turnovers in the final 1:30.
The Beavers (17-13 overall, 8-10 Pac-12) needed a win to go .500 in conference play for the second time in 25 years. They have lost six of seven.
The Beavers and Ducks play next week in the Pac-12 tournament in Las Vegas.
The Associated Press contributed to this report.