• Phils, Astros complete Giles deal
It originally was a club option, but it becomes a mutual option following the trade. If Morton declines his half of the option, he would lose a $1 million buyout.
Whitehead, 23, went 9-11 with a 4.44 ERA in 25 starts for Class A Advanced Clearwater last season.
The Phillies continue to add starting pitching depth. They acquired right-hander Jeremy Hellickson in a similar deal last month. Hellickson becomes a free agent after next season, and the Phillies sent a fringe prospect to Arizona to complete that deal.
• Hot Stove Tracker: Free agents and trades
Hellickson and Morton provide a veteran presence to mostly inexperienced rotation candidates that include Aaron Nola, Jerad Eickhoff, Adam Morgan, David Buchanan, Alec Asher and Severino Gonzalez. The Phillies could add more rotation depth if they complete the Giles trade, which is pending physicals.
It also gives the Phillies two potential trade chips in July, while they allow the organization's pitching prospects to continue to develop at a more natural pace.
The Phillies designated right-hander A.J. Achter for assignment to make room for Morton on the 40-man roster. They claimed him off waivers from the Twins on Nov. 20.
The Phillies signed right-hander Ernesto Frieri to a Minor League contract with an invitation to Spring Training. Frieri, 30, will compete for a bullpen job. He went 1-0 with a 4.63 ERA in 22 appearances last season with the Rays. He has a 3.55 ERA and 73 saves in 298 appearances in his career, making him a closer candidate.
Todd Zolecki is a reporter for MLB.com. Read his Phillies blog The Zo Zone, follow him on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.