The Diamondbacks designated Littell for assignment Sunday.
The veteran right-hander joined Arizona on a one-year contract Aug. 9 after parting ways with the Nationals, but he's been dumped from the big-league roster after surrendering 10 earned runs across 12 frames out of the bullpen. Littell has a 5.21 ERA, 1.41 WHIP and 73:39 K:BB over 124.1 innings overall this year, and he's unlikely to generate much interest outside of teams in desperate need of rotation innings.