This will probably happen dozens of times this year, but it turns out I was wrong about something. Looks like having Jai Miller is worse than having an empty spot on the 40 man roster. The A's have designated him for assignment. At Sacramento, he was 4 for 34 with 3 walks and 19 strikeouts. Yikes.
I'm not sure if the A's are making room on the 40-man roster for someone else or not, but will update this post if they are.
UPDATE: The A's placed Travis Buck on the DL and called up Matt Carson from AAA. Carson needed to be added to the 40-man roster, which is why Jai Miller was designated for assignment. Carson was hitting .357/.400/.464 in Sacramento.