The Diamondbacks designated Keuchel for assignment Wednesday, Jeff Passan of ESPN.com reports.
Keuchel caught on with the Diamondbacks after he was DFA'd by the White Sox earlier this year, but he will once again find himself a free agent after he likely clears waivers following his removal from the 40-man roster Wednesday. The left-hander owns a 8.53 ERA and 2.03 WHIP with 38 strikeouts over 50.2 innings in 12 starts with Chicago and Arizona this season.