Caissie hasn't been in the lineup the last two days due to neck spasms, MLB.com reports.
The 24-year-old likely would have sat Wednesday anyway against southpaw Noah Cameron, but Caissie's absence Thursday against right-hander Michael Wacha was a hint that something was amiss. He was apparently available off the bench for the series finale in Kansas City, although he went unused. Caissie will likely sit again Friday against lefty Shota Imanaga, but if he continues to improve he could slot back in as the right fielder Saturday with Clay Holmes on the bump for the Cubs.