ATLANTA — The Mets will likely play their next month of games without an essential piece of their infield. Luis Guillorme, who left Sunday’s game with groin tightness, has officially been diagnosed with a moderate strain in that left groin. The Mets gave a four-to-six week estimate for his return. Deven Marrero, a 31-year-old right-handed hitter with 173 big-league games under his belt, was called up from Triple-A Syracuse to take Guillorme’s spot on the roster.