"There's a few different players, but we're still representing New Zealand, regardless of who is turning out," Hesson said.
"Whether players are missing through injury [Corey Anderson and Trent Boult] or workload management [McCullum and Tim Southee], those selected are still expected to do a good job. We have expectations of them to put in good performances."
Two 23-year-olds, Northern Districts allrounder Mitchell Santner and Central Districts left-arm seamer Ben Wheeler, made their starts on the recent tour to England and both caught the eye.
Hesson liked what he saw from both and is keen to get more cricket into them to further what for now is just high promise.
Santner played all five ODIs in England, batting between No 5 and No7 and taking seven wickets with his left-arm spin at a respectable rate, especially in a series which was all bat and no balls, so to speak.
Wheeler played three games in that series and with his ability to swing the new ball, reverse swing the old, allied to a lively bouncer, he displayed his potential.
His issue had been staying fit, given a catalogue of injury breaks. This trip shapes up as a big opportunity to push his case in a crowded fast-medium department.
Speedster Adam Milne, out since midway through the World Cup with a foot injury, and allrounder Jimmy Neesham, missing for just over five months with a stress fracture, are welcome returns while there is merit in splitting the tour between legspinner Ish Sodhi (for the Zimbabwean leg) and seamer Doug Bracewell (for South Africa only).
The tour will certainly be a test of New Zealand's depth. McCullum is coming to the end of his international days and the amount of cricket dictates the need to broaden the base.
"With the amount of cricket in three forms of the game you can't keep reeling out the same players. We need to find out about players and they still have to perform. That'll be another challenge for this group," Hesson said.
Stand-in captain Kane Williamson gets another chance to work on his leadership skills. That temporary tag is likely to disappear in around a year's time.
NZ tour schedule
Aug 2: 1st ODI v Zimbabwe, Harare
Aug 4: 2nd ODI v Zimbabwe, Harare
Aug 7: 3rd ODI v Zimbabwe, Harare
Aug 9: Only T20 v Zimbabwe, Harare
Aug 14: 1st T20 v South Africa, Durban
Aug 16: 2nd T20 v South Africa, Centurion
Aug 19: 1st ODI v South Africa, Centurion
Aug 23: 2nd ODI v South Africa, Potchefstroom
Aug 26: 3rd ODI v South Africa, Durban
New Zealand squad to tour Zimbabwe and South Africa: Kane Williamson (c), Martin Guptill, Tom Latham, Ross Taylor, Grant Elliott, Colin Munro, Luke Ronchi, Jimmy Neesham, Mitchell Santner, Nathan McCullum, Ish Sodhi (Zimbabwe only), Doug Bracewell (South Africa only), Mitch McClenaghan, Matt Henry, Ben Wheeler, Adam Milne.