The Senators were chronically short of funds and never developed a strong farm system, forcing Selkirk to acquire players (such as the great slugger Frank Howard) through trades and fill out the roster with waiver-price acquisitions. Nonetheless, Washington improved every year from 1963 through 1967, but when the team's field manager, Gil Hodges, departed for the New York Mets after the '67 campaign, the Senators regressed and fell back into the American League basement. The death of one of the club's owners forced the sale of the team in the autumn of 1968, and Selkirk was fired during the transition. He then returned to the Yankees as a scout.
He was, arguably, the greatest Canadian-born baseball player of the first half of the 20th century.
Selkirk is mentioned in August Wilson's 1987 Pulitzer Prize-winning play, "Fences." The protagonist, Troy, confident that he can do better than white ballplayers in the majors, alludes to Selkirk and his .269 average.