MIAMI — The Miami Marlins are in agreement with Rachel Balkovec to be the organization’s director of player development, a source confirmed to the Miami Herald on Tuesday. A formal announcement is expected later this week. Balkovec, 36, has spent the past two seasons as the manager of the Tampa Tarpons, the Single A affiliate for the New York Yankees. She was the first woman to work as a full-time manager for an MLB-affiliated team. Balkovec also previously served as the hitting coach for the Yankees’ Florida Complex League team and as a minor league strength and conditioning coach — the first…