McCullum has been particularly impressed with two players who made their Test debuts during the series.
Wicketkeeper Jamie Smith finished with 14 catches and made 207 runs in four innings at an average of 51.75 having been given the nod over Surrey team-mate Ben Foakes and an out-of-form Jonny Bairstow.
The 24-year-old made an impressive 95 in the first innings at Edgbaston which helped England rebuild from a perilous position at 54-5.
McCullum said Smith’s ability to do “unselfish things” when batting with the tail stood out.
“When you’re in that position at seven and wicketkeeper you’re like the drummer in the band,” the Kiwi explained.
“You need to be prepared to take risks and he’s happy to do that, and he backs himself that he’s got the power game when the field is out.
“No [criticism of] guys that have been before, they’ve done great jobs for us, but we identified that it was an area where we wanted to add a little bit more punch.”
Stokes said Smith was “incredibly tidy behind the stumps” but “without really being noticeable”.
“He’s come in and done exactly what we’ve seen in him as a batter, in terms of the role batting down at number seven,” Stokes added.
“The two big innings were a great sign of him understanding that role without really having any experience doing it. He’s been phenomenal in this series.”