During his minor league career, Stapleton compiled a 30–26 record with a 3.43 earned run average (ERA) in 444 innings pitched.

During his professional career, he was listed at a height of 6 feet 1 inch (185 cm) and a weight of 185 pounds (84 kg).

[1] He posted a 16–5 record with a 3.28 earned run average (ERA) in his two years on the school's baseball team, who won the National Association of Intercollegiate Athletics Championship in 1982.

[2] As a member of the school's 1982 baseball team, Stapleton is enshrined in Grand Canyon University's athletic hall of fame.

A few months into the 1985 season, after losing his closer job to Jeff Parrett, he and his wife, Patty, told manager Tom Gamboa he wanted to quit baseball and become a chimney sweep.

With the El Paso Diablos of the Texas League that year, he compiled a 6–2 record with a 3.15 ERA in 38 relief appearances.

[6] He made his Major League Baseball debut that day, earning a win in 31⁄3 innings pitched against the New York Yankees.

[9] He made his season debut that year against the Boston Red Sox, pitching 12⁄3 innings, giving-up no runs on two hits.

[16] From February 2014 through 2024, Dave has worked in the California Angels as minor league coach and in player development.