It’s certainly a few weeks earlier than they preferred to do it, but the Royals revealed Thursday that they’re calling up Eric Hosmer to take over as their first baseman.

Kila Ka’aihue, who was hitting .195/.295/.317 with just six RBI in 82 at-bats, is getting sent down to open up a spot.

Hosmer was tearing up PCL pitching, hitting 439/.525/.582 with three homers for Omaha. He had a 16/19 K/BB ratio in 98 at-bats, and he was even 3-for-3 stealing bases.

The 21-year-old Hosmer was selected third overall in the 2008 draft out of a Florida high school. He started slow and batted just .241/.334/.361 with six homers in 434 at-bats for two A-ball teams in 2009, but he blossomed last year, hitting .338/.406/.571 with 20 homers between high-A Wilmington and Double-A Northwest Arkansas. That led the Royals to promote him to Triple-A to begin this year, and his remarkable first month followed.

As discussed here last week, the Royals didn’t want to go to Hosmer so early because doing so means he’ll surely be eligible for arbitration after 2013 if he stays in the majors. Promoting him now figures to cost the Royals several million dollars over the next seven years, since he’ll be eligible for arbitration four times, rather than the usual three.

The Royals, though, are trying to rebuild a fanbase, and it didn’t look like Hosmer had anything left to learn in the minors. Calling him up now figures to put some extra fannies in the seats, and the Royals could sign him to a long-term deal at some later date to mitigate the salary damage. Credit the franchise for making the move rather than waiting the extra month.

As for Ka’aihue, well, he had what was probably his one big chance and failed to take advantage. At 27, he’s not necessarily going to be buried for good. The Royals, though, won’t have any further need for him if Hosmer can establish himself. Japan might be his eventual destination.