In Loun's major league debut (September 23, 1964), he pitched a 1-0 complete game shutout against the visiting Boston Red Sox, allowing just five hits and no walks. Only 1,491 fans were in attendance at D.C. Stadium to witness this excellent effort by the 23-year-old rookie.
His next start was also against the Red Sox, this time at Fenway Park. (October 3, 1964) This time he allowed eight hits, three walks, and four runs (three earned) in just four innings pitched. He was replaced by a pinch hitter in the top of the 5th, so he left the game trailing 4-0. The final score was 7-0.