Middleton (personal) is listed among the Cardinals' available relievers for Monday's Grapefruit League game against the Nationals, Katie Woo of The Athletic reports.
While it's unclear if St. Louis plans on having Middleton work behind starter Miles Mikolas on Monday, the fact that Middleton is on the lineup card is an indication that he's reported back to camp after taking some time away from the Cardinals late last week to tend to a personal matter.