New Zealand director of cricket John Buchannan has appealed to critics to ease calls for the sacking of Brendon McCullum and Mike Hesson and captain and coach, saying they need stability in the wake of their series defeat to South Africa.

The Black Caps were comprehensively beaten by the world's number one Test side in both matches, losing by more than an innings each time. McCullum was skippering his first matches since the sacking of Ross Taylor, which caused much displeasure.

Taylor is New Zealand's premier batsman, and in the wake of his being stripped of the captaincy, which was done in a manner that NZC later apologised for, he refused to go on the tour to South Africa. He said he needed time to get his head right and would be back for the visit by England.

But Buchannan has refused to say that McCullum's appointment was a mistake, and that the skipper and Hesson have what it takes to move the side forward. He emphasised that the pair got along well, while it is known that Hesson and Taylor did not.

Buchannan told ONE News: "I'm not going into whether it was a mistake or not a mistake (to replace Ross Taylor with McCullum) but we have a new captain in there - Brendon McCullum.

"I know he and Mike Hesson work very well together. Listening to Brendon's interview this morning, as a captain of the side, he was very pleased with the way the group has responded in very trying situations."

The big boss also addressed Taylor's return to the side, but surprisingly said that it wasn't a foregone conclusion. It is expected that the former skipper, statistically their most accomplished Test batsman, will be back for the series against England, but Buchanan insisted he would need to prove himself again on the domestic circuit.

Also mentioned was Jesse Ryder, who has been out of the Black Caps side for nearly a year after taking time off to deal with personal issues. He has been in good form domestically, and will be hopeful of a recall.

Buchannan added of Taylor's return: "We haven't quite crossed that line yet.

"Ross has to go out and play some domestic cricket, Jesse is obviously playing domestic cricket, and certainly playing well in the short format of the game, and then a couple of the injured boys, our Vettori's and our Southee's, and we want them playing as well when they are ready."