In a breakout international summer, Cox impressed by scoring fifties in all three Tests when picked to bat number three against Pakistan. He also hit 76 against Sri Lanka when deputising for Buttler in the third ODI at The Oval on Sunday.
“I thought it was quite a Jos Buttler innings,” McCullum said.
“He has done really well domestically for a number of years and has been unlucky with injuries.
“For him to have the type of summer he has had and be in the position he is in, he deserves it.
“He is a phenomenal talent, is very well liked in dressing room as well and seems to be one of those guys who is good at everything he does, which will be incredibly annoying.”
England will also make a decision on whether to pick bowler Brydon Carse to tour Pakistan. He has not been selected since being arrested then de-arrested on a night out in Derby in August.
After a police investigation ended without action, he is now subject to a Cricket Regulator investigation and, while he remains available for selection, white-ball captain Harry Brook said last week he needs time away from the international scene.
McCullum, who began the summer as England’s coach across the three formats before being sacked from the Test role in July, dismissed any suggestion of regret at the end of the English season.
“I loved coaching all three formats,” he said. “Things move on, times change. I am biased but I genuinely think [new Test coach] Stephen Fleming will do an unbelievable job with the red-ball side.
“With the extra bit of time it probably does allow you to drill down on a few aspects you have identified you need to improve or shape things differently to get to where you want to.”
There will be Test Match Special commentary on England’s white-ball tours to Pakistan and Australia this autumn
