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In a week filled with roster upheaval, the Mets made four more moves prior to Friday’s game against St. Louis. This time, it was a simple pair of swaps for the Mets, all of which occurred in the battery.

Behind the plate, Josh Thole was activated off the 15-day disabled list after missing more than three weeks with a concussion. Thole was originally placed on the 7-day concussion DL on May 8 after taking a blow to the head from Philadelphia’s Ty Wigginton the previous day, and was transferred to the 15-day DL on May 22. He was hitting .284 with one home run and seven RBI before the injury.

Rob Johnson, who had been called up from Triple-A to replace Thole on May 8 and hit .313 in 32 at-bats, was sent back to Buffalo in that corresponding move.

On the mound, the Mets designated pitcher Chris Schwinden for assignment and replaced him by purchasing the contract of reliever Elvin Ramirez from Buffalo.

The 24-year-old Ramirez was signed by the Mets as a free agent out of the Domincan Republic in 2006 and has spent his entire career in the franchise’s farm system. After missing all of 2011 with a shoulder injury, Ramirez was 3-1 with a .065 ERA and a career-high 11.4 K/9 ratio in 19 outings between Double-A Binghamton and Buffalo this season.

Schwinden, meanwhile, was in his third 2012 stint with the Mets, and was 0-1 with a 12.46 ERA overall. He had been recalled from Buffalo on Tuesday, and allowed two runs in 2/3 IP in Wednesday’s loss to Philadelphia.

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