Buck Showalter thinks the mission involved the short-season Aberdeen IronBirds. He sent former Orioles star and coach Brady Anderson on a stealthy operation to see teenager Manny Machado do a few laps with the under-the-radar farm club. The talent was obvious. The experience? The mental makeup? Those tricky and hard to define intangibles? “I remember Brady Anderson going over there and sitting on him for a few days to see if he thought he was ready to come up and help us at third base,” said Showalter, whose Mets will face Machado and the Padres in a NL wild-card opener Friday at Citi Field. “…