He had missed nearly a month of action that season after his thumb was dislocated by a John Roseboro line drive single on June 21.

[1] 1968, the "Year of the Pitcher," was Washburn's best season; he posted a 14–8 record with a 2.26 earned run average in a Bob Gibson-led rotation as the Cardinals repeated as National League champions.

Washburn slumped to 3–8 as a spot starter during the 1969 season, after which the Cardinals traded him to the Cincinnati Reds for another 1968 no-hit pitcher, George Culver.

In his career, Washburn won 72 games and lost 64 with a 3.53 earned run average and struck out 700 batters in 12092⁄3 innings pitched.

In 1972, Washburn managed the Seattle Rainiers, a co-op team in the Class A Northwest League, before accepting a teaching position the following year at Bellevue Community College.