Basically a line drive hitter and smart baserunner, Regan had good contact and was able to convert his gap line drives into extra bases.
In 1927 he recorded career-numbers with 37 doubles and 10 triples, while hitting .274 in 129 games.
His most productive season came in 1928, when he posted career-highs with seven home runs and 75 RBI, while collecting 30 doubles and six triples. On June 16 of that year, he came to bat twice in an inning and homered both times. His second was an inside-the-park homer, as he equaled his HR output of the previous season. Besides this, he was considered in the American League MVP vote in both years.
In 1929 Regan hit a career-high .288, while collecting 54 RBI. A year later he was still productive hitting 35 doubles, and 10 triples. He also played with the Pirates in 1931, his last major league season.
In a six-year career, Regan was a .267 hitter (632-for-2364) with 18 home runs and 292 RBI in 641 games, including 236 runs, 158 doubles, 36 triples, 38 stolen bases, and a .306 on-base percentage. He made 610 appearances at second base, and committed 138 errors in 3610 chances for a .965 fielding percentage. Eventually, he appeared in 14 games at third base (12), first (1), and right field (1).
Following his retirement, Regan worked in the Allegheny County (PA) police department for 20 years and also joined the armed forces during World War II.