An MRI revealed patellar tendinitis in Perez's right knee. The Mets plan to send the southpaw to Port St. Lucie, Fla., on Sunday.
Perez made one start in Buffalo last Tuesday, throwing 88 pitches in 4 1/3 innings. Although he allowed just one run on three hits, Perez walked five batters, not exactly erasing concerns about his mechanics.
"All that stems from the knee," manager Jerry Manuel said. "He can't be consistent with his fundamentals."
Perez struggled mightily in five starts with the Mets after signing a three-year contract to remain with the team in the offseason. Perez was 0-2 with a 9.97 ERA before being demoted to the bullpen and eventually placed on the disabled list on May 7.
Tim Britton is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.