Ish Sodhi is capable of making the biggest difference for New Zealand in the 14 tests between now and March.
It might require imagination, given his test record of 27 wickets at 52.81, but anyone watching him live knows those statistics are as deceptive as his googly. He spins the ball both ways and offers useful lower-order batting.
Captain Kane Williamson, Ross Taylor, BJ Watling, Trent Boult and Tim Southee come with established test expectations but, if Sodhi delivers quality leg spin, New Zealand's chances strengthen towards breaking overseas series victory droughts of 62 and 60 years in South Africa and India respectively.
His first assignment is likely to be in Bulawayo against Zimbabwe on Thursday, when the first test starts.
Sodhi's impact springs to mind after watching Pakistan leg spinner and the new No 1-ranked test bowler Yasir Shah rip through England at Lord's last week. He earned match figures of 10 for 141 in his first test outside Asia on a relatively tame pitch. The revolutions and variations generated via Yasir's wrist negated that.
It proved leg spinners can be men for all seasons and conditions.
Yasir struggled on the first day of the second test in Manchester yesterday, but his presence is a perpetual threat. He has failed to take a wicket in one innings of his 14 tests and his strike rate of 49.1 leaves him fourth among current players behind pace bowlers Dale Steyn, James Pattinson and Vern Philander.
New Zealand know Yasir's power, too. He was the top wicket-taker with 15 at 33.53 in their 2014 drawn series across the United Arab Emirates.
His performance rekindled memories of watching Shane Warne mature (as a cricketer). Who didn't want to get into the backyard and rip good-length balls into the top of off stump from a foot outside leg, like his 1993 'ball of the century' to Mike Gatting at Old Trafford?
No one is expecting Sodhi to perform miracles, but if he continues the form which saw him take New Zealand to the semifinals of the World T20 with 10 wickets at an average and strike rate of 12, he will become the team's prized asset.
Sodhi sums up his test role as "putting the ball in the right place for long periods and making sure there's energy behind the ball".
That's a modest take on his art. He must create enough of an illusion, by flighting the ball above the batsman's eyeline, to evoke temptation. Simultaneously he's trying to drift the ball laterally across the batsman to generate further doubt.
He needs the backing of tight bowling from the other end from Boult, Southee and whichever seamer or spinner assumes the remaining specialist position. Williamson must show confidence in Sodhi's ability when he can by camping fielders around the bat. All those factors could combine to make Sodhi unplayable.