On July 24, 2014, the Blue Jays traded McGuire to the Oakland Athletics for cash considerations.[10] He was optioned to the Sacramento River Cats of the Class AAA Pacific Coast League (PCL). When the Athletics acquired Adam Dunn on August 31, McGuire was designated for assignment and assigned outright to Sacramento. McGuire was released from the Athletics organization before the start of the 2015 season.[11]
On November 26, 2015, McGuire signed a minor league contract with the St. Louis Cardinals.[15] He began the 2016 season with the Triple–A Memphis Redbirds of the PCL,[16] and also made one appearance for the Double–A Springfield Cardinals. In 26 starts for Memphis, McGuire registered a 7–11 record and 5.10 ERA with 111 strikeouts across 134 innings pitched. He elected free agency following the season on November 7, 2016.[17]
Cincinnati Reds
On February 20, 2017, McGuire signed a minor league contract with the Cincinnati Reds.[18] He pitched for the Pensacola Blue Wahoos of the Double–A Southern League.[19] On September 12, the Reds promoted McGuire to the major leagues.[20] He appeared in six games for the Reds in 2017, and pitched to a 1–1 record, 2.63 ERA, and 11 strikeouts in 132⁄3 innings.[21] On November 3, McGuire was removed from the 40–man roster and sent outright to Triple-A.[22] He elected free agency on November 6.
Toronto Blue Jays (second stint)
On November 16, 2017, McGuire signed a minor league contract with an invitation to spring training with the Toronto Blue Jays.[23] On May 13, 2018, McGuire was brought up to the Blue Jays.[24] He was designated for assignment on June 9.
Los Angeles Angels
On June 15, 2018, McGuire was claimed off waivers by the Texas Rangers and immediately optioned to Triple-A.[25] Three days later, he was designated for assignment. On June 19, McGuire was traded to the Los Angeles Angels for cash considerations or a player to be named later. In 17 games, he collected an ERA of 6.07 in 29+2⁄3 innings. He elected free agency on November 2, 2018.[26]
Samsung Lions
On November 29, 2018, McGuire signed a one-year, $950,000 contract with the Samsung Lions of the KBO League.[27] On April 21, 2019, McGuire threw a no-hitter against the Hanwha Eagles, striking out 13 batters en route to a 16–0 win.[28] McGuire was released by the Lions on August 7, 2019, following the signing of Ben Lively.
Tampa Bay Rays
On February 14, 2020, McGuire signed a minor league deal with the Tampa Bay Rays. He did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[29] McGuire was released by the Rays organization on May 28.
On May 25, 2022, McGuire's contract was purchased by the Cincinnati Reds organization.[32] In 20 games (14 starts) for the Triple-A Louisville Bats, he posted a 4-5 record and 6.32 ERA with 60 strikeouts across 74 innings of work. McGuire elected free agency following the season on November 10.[33]
McGuire announced his retirement from baseball on December 16, 2022.[34]