Over the next eight seasons, Selkirk batted over .300 five times, twice drove home more than 100 RBIs, played in five World Championships (1936, 1937, 1938, 1939 and 1941), and made the American League All-Star team in 1936 and 1939.

[1] A native of Huntsville, Ontario, Selkirk batted left-handed and threw right-handed, standing 6 feet 1 inch (1.85 m) tall and weighing 182 pounds (83 kg) (13 stone).

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 1967 campaign, the Senators regressed and fell back into the American League basement.

The December 1967 death of James M. Johnston, one of the club's two principal owners, forced the sale of the team in the autumn of 1968, and Selkirk was fired during the transition.