Bowling alongside quicks like those in the South African camp gives Tahir a boost anyway - batsmen are far more likely to get out to the legspinner if they survive the pace examination - and he gives the Proteas a dimension they haven't had since the days of Paul Adams: an attacking spinner.
There will be little relief for the Black Caps once the new ball has lost its shine; even less if grounds are prepared that benefit Tahir in a cricketing equivalent of Catch-22.
So how has such a talent played so little international cricket, and why is he playing for South Africa and not his native Pakistan?
The answer is wanderlust ... and love. Tahir became a leading cricket nomad, playing for a vast number of different teams. He started at 19 and the love of travel while playing cricket stuck.
But it wasn't as profound as the love he felt for Saumaya Dildar in 1998, when Tahir was playing in South Africa at the Under-19 World Cup.
He met Saumaya on tour and began an eight-year long-distance romance before he moved permanently to the Rainbow Nation to get married in 2006. No mercenary, he changed nations for his woman.
Then began the long process of qualifying for the national team. It came on December 10, 2010 - but not after a period of considerable embarrassment.
Someone got their dates wrong and Tahir was named to play against England in South Africa's home series in January 2010, before it was discovered that he wasn't actually eligible until December 10 that year - nearly five years after he married Saumaya. He was discreetly withdrawn.
"Initially, I was almost crying with happiness because I was going to share the dressing room with Graeme Smith and Jacques Kallis," he said at the time. "I had to wait for 10 years [since he began playing senior cricket] but finally I have got the recognition."
Tragically, his mother in Pakistan was ill - and lived to see her boy named in the South African squad. But she died before word made it home to Lahore that he had been found ineligible.
Somehow the call to play for Pakistan never quite came when Tahir was on his travels. When Waqar Younis took him aside to ask him to play for Pakistan when his South African eligibility made headlines, Tahir turned him down. He'd made his choice.
He made his debut in last year's World Cup - and played against New Zealand in that ill-fated (for South Africa) quarter-final when their batting failed and Jacob Oram had his defining one-day moment for New Zealand as a bowler.
Tahir took two for 32 off nine overs in that match (dismissing Ross Taylor and batting hero Jesse Ryder for 83). Although he can be a good attacking/containing bowler in the one-day game (14 wickets for 150 runs at an average of 10.71), the Proteas clearly see him as a trump card in the tests. He was wicketless in his debut - the test when the South African quicks bundled Australia out for 47 in November - but took three for 55 off 14 overs in the next.
His test record is so far unremarkable (that three for 55 is his best bowling so far) and he took 10 wickets in the three-test series against Sri Lanka, with his best being three for 106 off 32 overs on a seamer-friendly pitch.
Altogether, he has taken 14 test wickets at an average of 36.78; hardly Warne-esque figures - but there are many dangers in that spinning wrist of his. Perhaps a better guide, at this stage, is the 615 wickets he has taken in all first-class cricket at an average of 25.64
He is one of three Muslims in the side (Hashim Amla and recent convert quick bowler Wayne Parnell are the others). Anyone who doubts that Tahir could be a key factor in the tests should know that his presence has buoyed virtually every side he has played for thus far - including South Africa's Titans (six out of seven championships with Tahir on board) and English county sides.
He will also, perhaps, be the only player in the coming test series striving to complete the gift he never got to give to his mother.
