Veteran left-hander Dallas Keuchel has been designated for assignment by the Arizona Diamondbacks after struggling in his only four starts, sources told ESPN's Jeff Passan on Wednesday.

Keuchel had been DFA'd earlier this year by the White Sox and caught on with the Diamondbacks after being signed to a minor-league contract in early June, but was winless in four starts with a 9.64 ERA. He'll clear waivers and be a free agent again.

The 34-year-old Keuchel won the AL Cy Young Award with the Houston Astros in 2015 and is also a two-time All-Star and five-time Gold Glove winner.

When Keuchel was added to the Diamondbacks' 40-man roster, Arizona became responsible for only a prorated share of the $700,000 major league minimum, and the White Sox remained responsible for the rest of his $18 million salary this season. Chicago also owes a $1.5 million buyout of a 2023 option.

The Associated Press contributed to this report.