Avery: I'm training to be an engineer trifecta andro kit log The Mets have helped MLB developers test the app at Citi Field over the summer—the beacons have to be refined under normal crowd conditions to make sure they work when masses of people are clustered around. MLB will continue to test and finish the upgraded app during the off-season, then show it to other clubs around the country. Each stadium will have different beacons providing a different experience, and it’s up to each ballpark to decide whether to adopt the new technology.