In 39 appearances out of the bullpen for the two affiliates, he compiled an 0–2 record and 5.19 ERA with 52 strikeouts and 3 saves across 67+2⁄3 innings of work.

Thielbar split the 2012 campaign between Fort Myers, the Double–A New Britain Rock Cats, and Triple–A Rochester Red Wings, accumulating a 6–2 record and 2.43 ERA with 74 strikeouts and 6 saves across 48 appearances.

[8] He remained in the Twins bullpen for the remainder of the season, appearing in 49 games and pitching 46 innings with a 1.76 ERA and 0.826 WHIP.

[11] The Padres assigned him to their Triple-A affiliate, the El Paso Chihuahuas, for whom he pitched 12+1⁄3 innings, giving up only one earned run.

[13] On March 29, 2016, Thielbar signed with the St. Paul Saints of the American Association of Independent Professional Baseball.

He split the season between the Double–A Erie SeaWolves and the Triple–A Toledo Mud Hens, and was a combined 7-1 with a 2.05 ERA in 57 innings.

[17] After the season, on October 10, he was selected for the United States national baseball team in the 2019 WBSC Premier 12.

[22] Thielbar made 67 appearances out of the bullpen for the Twins during the 2022 season, accumulating a 4-3 record and 3.49 ERA with 80 strikeouts across 59+1⁄3 innings pitched.

[23] On January 13, 2023, Thielbar agreed to a one-year, $2.4 million contract with the Twins, avoiding salary arbitration.

[25] In 59 relief appearances for the team in 2024, Thielbar logged a 5.32 ERA with 53 strikeouts and 3 saves across 47+1⁄3 innings pitched.