As a sixteen-year-old,Deal was invited by the Pittsburgh Pirates to spend in week in Pittsburgh. By then,the club was managed by Pie Traynor,who gave Deal his first baseball tryout. After signing with Pittsburgh,he spent 1940 with the Hutchinson,Kansas team of the Western Association,hitting a .312 average while splitting time between the outfield and third base. The next year he gained promotion to the Harrisburg Pirates of the Interstate League,playing for them two seasons before joining the military. In 1945,he played in the International League with the Toronto Maple Leafs as a pitcher,and was sold to the Boston Red Sox in 1947. Late in the season he was called up to the Red Sox,making his debut on September 11 as a pinch-hitter. In his first major league at bat,he connected a game-winning RBI single off Cleveland Indians pitcher Bob Lemon,while posting a 0–1 mark in five appearances.
Deal earned a spot as a starting pitcher during 1948 spring training,but hurt his arm after that. He would eventually pitch in four games with the Red Sox that year and went 1–0 with a perfect 0.00 ERA in 4 innings of relief. In 1949 he was traded by Boston to the St. Louis Cardinals in exchange for a minor leaguer. He spent 1949 with the Columbus Red Birds of the American Association and later pitched in 36 games for the Cardinals in 1950 and 1954.
In four major league seasons Deal posted a 3–4 record with a 6.55 ERA in 45 games,including two starts,34 strikeouts,48 walks,12 games finished,one save,and 89