Jepsen earned his first All-Star selection in the minor leagues, and was enjoying his finest season to date with a combined 3–4 record, 13 saves, a 1.87 earned run average and 55 strikeouts for the Arkansas Travelers and Salt Lake Bees when he was selected to play for the United States national baseball team at the 2008 Summer Olympics.

[1] Jepsen made his major league debut against the New York Yankees on September 8, 2008, at Angel Stadium in Anaheim, California.

He pitched one inning in a blowout game, retiring Derek Jeter, Bobby Abreu, and Alex Rodriguez in order.

[4] On July 31, 2015, the Minnesota Twins acquired Jepsen for Chih-Wei Hu and Alexis Tapia.

On July 3, he was designated for assignment after posting an ERA of 6.16 while recording just 7 saves for the last place Twins.

[8] In 2016, balls hit against him had the highest average exit velocity in the major leagues, at 91.7 miles per hour.

[11] Nearing a return after losing the first half of the season to a quadriceps injury, Jepsen reportedly signed a minor league deal with a July 26 opt-out date on June 29, 2017, to join the Washington Nationals organization.