The performance earned him a promotion to the Senators' 40-man roster in September. Among his seven games with Washington, he made two starts: September 10 against the Kansas City Athletics and September 16 against the Baltimore Orioles. His debut start was the better of the two. He pitched seven innings and gave up four runs, all earned, and four hits, one of them a solo home run by Kansas City's Gus Zernial. He held a 5–1 lead through seven innings, but walked the bases loaded in the eighth frame and was removed from the game. The Senators' relief pitchers, Chuck Stobbs and Pedro Ramos, then gave up the tying runs and ultimately lost the game, 8–6.[1] Clarke's seventh and last MLB game, September 24 against the Orioles, was his finest: appearing in relief, he set down all nine Baltimore batters he faced over three innings.[2]
During his MLB trial, Clarke allowed 17 hits, 11 earned runs and 14 walks in 21+1⁄3 innings pitched, with nine strikeouts, no decisions to his record and an ERA of 4.64.
He returned to minor league baseball in 1956–1957 to finish his North American pro career, going only 14–32 and losing a combined 20 games in 1956 in the Sally League and Triple-AAmerican Association.
Webbo Clarke died at age 42 in Cristóbal, Colón, in his native Panama.
