In his two years with the Buckeyes, Arlin posted a 24–3 record with 294 strikeouts. His 165 strikeouts in 1965 remains an Ohio State single-season record; it and the career strikeout record had been set by Paul Ebert in the 1950s. Arlin's number 22 was the first to be retired by the Ohio State baseball team.
Pitching for a struggling young team, Arlin led the National League in losses in both 1971 and 1972 (19 and 21 respectively). In both seasons, however, he posted a respectable earned run average: 3.48 in 1971 and 3.60 in 1972. The 1972 season was an especially curious one for Arlin: he pitched a one-hitter, three two-hitters (in one, on July 18 against the Phillies, he had a no-hitter broken up by Denny Doyle with two out in the ninth—to date, the closest a Padre has come to pitching a no-hitter), and a 10-inning stint in which he allowed only one hit. Yet he finished 10–21. In 1973 Arlin recorded a personal best 11 victories against 14 losses, but with a 5.10 ERA—nearly a run and a half above his career ERA to that point. Midway into the 1974 season the Padres traded Arlin to the Cleveland Indians.
During his playing career, Arlin began practicing dentistry, and became a dentist after his playing career, in which he won 34 games (11 of which were shutouts) while losing 67, with 463 strikeouts and a 4.33 earned run average in 7882⁄3innings pitched.
With one out to go in that near no-hitter, Arlin had gotten two strikes on Doyle. Thinking Doyle was going to bunt, first-year Padres manager Don Zimmer ordered third baseman Dave Roberts to move up about eight feet on the grass. Doyle took advantage by slapping a ground ball that bounced over Roberts' head—a ball that Roberts could have fielded at normal depth. Doyle then advanced on a balk before scoring on a Tommy Hutton single; these would be the only two hits Arlin would allow in defeating the Phillies 5–1.