The Pirates have announced that they've optioned Jameson Taillon to Indianapolis and recalled Kyle Lobstein.
Neal Huntington was forthright about the possibility that Taillon's outing yesterday would be a spot start, but I'm still a bit surprised by this (even if Francisco Cervelli might have let the news slip last night). Huntington said roughly the same thing when Gerrit Cole was promoted, and Cole stuck. The Pirates can pretty clearly use Taillon and obviously need rotation help. Also, Super Two shouldn't really be a concern at this stage, so I don't think the Bucs are aiming to preserve Taillon's service time. Taillon's demotion ensures he won't be back until at least June 19, unless someone gets hurt.
The Bucs' bullpen did need to pitch four innings yesterday and six on Tuesday due to the doubleheader, however, so it could lean on Lobstein if they need extra help tonight. Also, as lucasmagalhaes points out in the comments, sending Taillon down for a bit allows the Pirates to limit his innings. Hopefully that's all that's going on here.