Rosen appeared in 22 games, starting one of them, batting .087 (2-for-23) with 3 runs scored, one double and a pair of RBI and stolen bases as a freshman at Washington State.
In high school, Rosen was a two-time All-WesCo League First Team selection as an outfielder, batting .500 as a senior. Rosen lettered in baseball, football and was also a standout swimmer, qualifying for the state tournament all four years.