Royals promote Alec Mills to be 26th man for doubleheader today, Whit Merrifield to be promoted?

The Royals have a day-night doubleheader today against the Boston Red Sox, to make up for Monday's postponed game. Per MLB rules, teams are allowed to call up a 26th man on the roster for doubleheaders. The Royals will reportedly call up right-handed pitcher Alec Mills from AA Northwest Arkansas to join the roster.

The 24-year old Mills was originally a 22nd-round pick by the Royals in 2012 out of the University of Tennessee-Martin. He has steadily moved up the system, and last year was named Royals Minor League Pitcher of the Year by going 7-7 with a 3.02 ERA and an impressive strikeout rate of 8.8 per-nine-innings with a minuscule walk rate of 1.1 walks per-nine innings for High A Wilmington.

This year, Mills had an ERA of 2.36 in seven starts for the Naturals with 44 strikeouts and just six walks in 42 innings. Here is what our Shaun Newkirk wrote about him last off-season:

Mills does not have a stellar arsenal, but he throws strikes as well as anyone in the system. It is not hard to see three average pitches with him - a fastball (which is already average or better), curveball, and a changeup. Mills was not particularly old for the Carolina League, and is a Tommy John surgery survivor.

Mills was already on the 40-man roster, so he will not require a corresponding roster move. He last pitched on May 13, so he is on regular rest as he was scheduled to pitch last night but was bumped to make room for Kyle Zimmer.

Update 12:32 PM: Whit Merrifield may be coming up too, although the transaction may not come until after the doubleheader. From his sister, Costner, on Twitter:

No official transaction has yet been announced. The "26th man" cannot be switched between games, so any move would likely come after today's games. Whit Merrifield was hitting .278/.342/.458 with five home runs in 36 games for Omaha. The 27-year old is capable of playing all over the field, playing primarily second base and the outfield. He is not on the 40-man roster, so the Royals would have to remove someone from the roster to make room for him.