I think it was related to how Miller was called up to the majors. They probably called him up for bullpen relief, so Yahoo (or whoever updates their database) listed him as a RP. He probably wasn't going to start anyway, but with the injury to Westbrook, he might get a shot. If he starts 3 games, he'll get SP eligibility again.
Changes can happen during the season, by the way, if players meet the requirements for the new positions. For pitchers, it's 3 starts (for SP) and 5 relief outings (for RP). For batters, it's 5 starts or 10 total appearances at a position.
he was a starter all year in the minors...he had i game as a reliever.
so i also have dylan bundy-sp, gerrit cole-sp, as reserves.so if they would get called up and make an apperance out of the pen then this too would change.I am sure postions can NOT be taken away during season.another example i have bastiua 3base/right field.i know he didnt play 3rd base this year but this wouldn't be changed till next year. thaanks for the feedback!