Bronstad threw and batted right-handed, stood 6 feet 3 inches (1.91 m) tall and weighed 196 pounds (89 kg) during his ten-season active career.

After signing with the Yankees in 1955, he moved up through the farm system of the Bronx Bombers until his recall in mid-1959, the least successful season of Casey Stengel's 12-year run as the club's manager.

He allowed six hits and three earned runs through seven full innings pitched, but the Yankee hitters couldn't solve Detroit left-hander Don Mossi, and Bronstad took the 3–1 defeat.

[1] In two other starts, Bronstad gained a no-decision June 18 against the eventual American League champion Chicago White Sox, but absorbed his second loss six days later against the second-division Kansas City Athletics, despite again allowing only three earned runs, this time over six innings.

Relieving Claude Osteen in the fifth inning with the Senators leading 3–2, he held off a Tigers threat and remained on the mound for the final out of Washington's 9–4 victory.