A progress report on Yankees’ Dellin Betances

BOSTON — Dellin Betances stretched out to throwing to 90 feet on flat ground Thursday at Fenway Park, as he makes his way back from the IL with the hope of returning at some point this season. “I threw 25 [pitches] at 60 [feet], 20 at 75 and five at 90,’’ said Betances, who hasn’t…