On August 9, 2020, Waddell had his contract selected to the 40-man roster. He made his major league debut on August 14 against the Cincinnati Reds.[9]
Minnesota Twins
On October 30, 2020, the Minnesota Twins claimed Waddell off of waivers.[10] On February 11, 2021, Waddell was designated for assignment following the waiver claim of Kyle Garlick.[11] On February 13, Waddell was outrighted and invited to spring training as a non-roster invitee.[12] On April 7, 2021, Waddell was selected to the 40-man and active rosters.[13] After recording an 11.25 ERA in 4 appearances, Waddell was designated for assignment on May 7, 2021.[14]
Baltimore Orioles
On May 8, 2021, Waddell was claimed off of waivers by the Baltimore Orioles.[15] Waddell pitched 1.0 scoreless inning for Baltimore before being designated for assignment on June 4.[16]
St. Louis Cardinals
On June 6, 2021, Waddell was claimed off waivers by the St. Louis Cardinals.[17] Waddell made 4 appearances for the Cardinals in 2021, going 0-1 with a 6.75 ERA and 7 strikeouts. On April 4, 2022, Waddell was designated for assignment by the Cardinals. He was outrighted to the Triple-A Memphis Redbirds on April 7.[18] He was released on July 13.
Doosan Bears
On July 17, 2022, Waddell signed with the Doosan Bears of the Korea Baseball Organization. He made 11 starts for Doosan down the stretch, logging a 5-3 record and 3.60 ERA with 40 strikeouts in 65 innings pitched.
Rakuten Monkeys
On January 14, 2023, Waddell signed with the Rakuten Monkeys of the Chinese Professional Baseball League.[19] On April 1, Waddell started an Opening Day victory for the Monkeys in his CPBL debut.[20] In 12 starts for Rakuten, he registered a 5–5 record and 3.30 ERA with 60 strikeouts in 71.0 innings pitched.
Doosan Bears (second stint)
On June 12, 2023, the Monkeys completed a contract transfer with the Doosan Bears of the KBO League, with Waddell set to report to Doosan on June 16 after one final start with the Monkeys.[21] In 18 starts for Doosan, he registered an 11–3 record and 2.49 ERA with 100 strikeouts across 104+2⁄3 innings of work.
On December 21, 2023, Waddell re–signed with the Bears on a one–year, $1 million contract.[22] In 2024, he posted a 7–4 record with a 3.12 ERA and 75 strikeouts across 75 innings pitched. Waddell became a free agent following the season.
New York Mets
On December 16, 2024, Waddell signed a minor league contract with the New York Mets.[23] He began the 2025 season with the Triple-A Syracuse Mets, posting a 1-1 record and 1.54 ERA with 21 strikeouts over his first five starts. On April 30, 2025, the Mets selected Waddell's contract, adding him to their active roster.[24] In 11 appearances for New York, he recorded a 3.45 ERA with 22 strikeouts across 31+1⁄3 innings pitched. Waddell was designated for assignment by the Mets following the acquisition of Drew Romo on December 17.[25] On December 19, he cleared waivers and was sent outright to Triple-A Syracuse.[26]
