Jesus Montero has played 29 games at catcher this season for the Mariners. He's batting .208/.264/.327 — that's not very good! — and struggling big-time as a catcher in the majors.
Jesus Sucre has played 14 games this season for the AAA Tacoma Rainiers. He's batting .302/.373/.321 — that's not bad! — and is known to be a solid defensive catcher.
And, according to The Tacoma News Tribune's Ryan Divish, Montero is being sent down to Tacoma, while Sucre is being called up. It's a Jesus-for-Jesus swap. There have probably been, like, Bill-for-Bill swaps, but there was never a Bill at the center of the world's largest religion. So, this seems more significant.