Whitlock (hip) will begin the season on the 10-day injured list, Chris Cotillo of The Springfield Republican reports.
Whitlock made his first spring training start Monday, but Red Sox manager Alex Cora said the 26-year-old righty will need to make three more starts before he's ready to rejoin Boston's rotation. Those three outings (plus four rest days between each start) put him in line to return sometime in mid-April.