Captain Brendon McCullum conceded New Zealand were entirely outgunned, after slumping to an innings and 193-run defeat in the second and final Test at St George's Park on Monday.

Trounced by an innings and 27 runs at Newlands in Cape Town earlier this month, the tourists continued their tragic form in Port Elizabeth, where they slumped to a series whitewash inside four days.

Without the injured Tim Southee and Daniel Vettori and batsman Ross Taylor, who withdrew from the tour after a fallout with new coach Mike Hesson, the Black Caps were an inferior unit throughout the two-match affair.

"It was a tough series against a number one side who are on top of the game. We have been well short of the mark. South Africa have been phenomenal in all departments," said McCullum.

"It is hard to put a finger on what went wrong. We wanted to compete well but it got the better of us. Our poor start at the first innings in both Tests put us on the back foot.

"When we came here, we wanted to perform well as a team. We are missing some key players but I am pleased with the attitude of some of the guys. We have been through some tough times and we hope to learn our lessons in the future.

The Proteas and Kiwis will soon meet for three ODIs, the first of which gets underway in Paarl on Saturday. "We are ready for the ODIs as this format is more to our liking. I hope that the new guys bring some enthusiasm to the team," concluded McCullum.