He's 31, has gone through significant injury setbacks in a career which began 11 years ago, and yet he reckons he's bowling as well as ever for Otago.
His 36 Plunket Shield wickets are second only to another seasoned performer, Northern Districts' Brent Arnel, and he was a key figure in Otago's HRV Cup triumph this summer with 11 wickets and an economy rate of 7.4 per over.
"My form's been really good all year in all forms. I don't think I've ever bowled as well as I have this year, and you never really lose sight of what you want to achieve," Butler said.
"My body is 10 times better than when I was 23. I look after it a hell of a lot better now. I try and tell people age is just a number. I still feel I've got four or five years left.
"I'm doing the right things off the park and certainly don't feel I'm anywhere near finishing."
Butler was counted out of the opening game in the ANZ international series, a 40-run win for England at Eden Park last Saturday, by a minor ankle niggle.
If he plays tonight it will complete a comeback which is thoroughly justified by the simple expedient that he's among the best seamers going around the country, and hits a long ball as a late-order bonus.
Butler was among the country's quickest bowlers in the early 2000s, pushing up to 150km/h.
In those days, pace was what mattered to him.
Butler reckons the big change for him this year was from being an into the wind "dot" ball bowler to chasing wickets.
He has dialled his speed back, but still rates himself about 140km/h.
It's all a far cry from the disillusioning times over the last 10 years, including the day his pen was poised to sign on the dotted line for an unnamed English county.
He thought hard about using his British passport and jacking in New Zealand cricket.
Otago, as they ponder the Champions League later this year, are grateful he had a late change of heart.
Butler is confident New Zealand will be on their game tonight after a poor bowling and fielding performance at Eden Park.
"T20 is a game where one or two players can take the game away from you and we've got as many match winners as they do."
England have a question mark over batsman Eoin Morgan, who didn't train yesterday after jarring his back late in New Zealand's innings on Saturday.
Both teams might fancy challenging the 23 sixes from the opening clash.
The Seddon Park boundaries are slightly longer straight than Eden Park, but the ground in the centre of the city has a distinctly smaller square.
nzherald.co.nz will have live updates of tonight's match from 7pm.
New Zealand v England
Second T20
Seddon Park, Hamilton, 7
tonight, live SS1
New Zealand (from): Brendon McCullum (c), Martin Guptill, Hamish Rutherford, Ross Taylor, Colin Munro, Grant Elliott, James Franklin, Nathan McCullum, Ian Butler, Ronnie Hira, Andrew Ellis, Mitchell McClenaghan, Trent Boult.
England (from): Stuart Broad (c), Michael Lumb, Alex Hales, Luke Wright, Eoin Morgan, Jonny Bairstow, Joe Root, Jos Buttler, Samit Patel, James Tredwell, Steven Finn, Chris Woakes, Jade Dernbach, James Harris.
