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.