In reply Cornwall stuttered to 224-6 with in-form batsman Michael Taiaroa unbeaten on 101, carving up seven fours and two sixes.
No doubt the visitors would have been kicking themselves for not performing the elementary task of ticking over the strike to a stranded Taiaroa.
"We dropped Mikey a couple of times and things weren't going our way and then something came out of the blue off JK's pads and took Jake [Smith] out," a relieved Diack said.
Smith (43 runs) went out somewhat fortuitously when he lunged at a delivery but missed.
The ball hit wicketkeeper JK Whyte's pad and rolled on to the stump, knocking off the bails and catching Smith shy of his crease.
"That was the start of the turn for us. We weren't panicking but we were starting to get a little worried."
Diack said death bowling in the nets had paid off. "Last summer it didn't come off, this year it did."
Cornwall beat NTOB last summer after rain-affected wickets prompted the shift to artificial strips at Park Island.
Diack and Taiaroa agreed they were about 20-odd shy of a decent total on a slow wicket.
While they had lost the New Zealand club champions qualifier, Diack was delighted with three titles out of four in his maiden season as captain.
"The boys backed me so it's very sweet."
NTOB also have won the senior men and women's title.
Taiaroa was distraught, finding little to celebrate about despite his third century this summer before he jets off to Ireland. "I'm gutted. You get a hundred and most times your team wins, but what can you say?
"I think through the middle period our batsmen didn't tick it around enough.
"When I wasn't facing I needed them to rotate the strike on the first or second ball so as to give me at least four balls to find the boundary."
Taiaroa had communicated that but his teammates couldn't execute the plan.
"In all fairness, they bowled very well in the last 10 overs so it was pretty difficult to punch out and we ended up blocking them for ones."
Andersen was the pick of NTOB bowlers, claiming 3-42 at 4.2 runs an over but a wicket-less Smidt (3.25) and Indika Senarathne (3.4 for a wicket) won the frugality stakes.
Ruahine Motors Central Hawke's Bay allrounder Paul Hindmarch won the premier player of the season award.
The English import, brother of Hawke's Bay United soccer player Stephen Hindmarch, relished taking wickets and eking out runs after a promising CHB bowed out of the semifinals but upset NTOB for national honours.
"It's obviously disappointing but from what I can gather it's the best season they [CHB] have had for a long time so it just shows there's a lot of talent among the lads here," Hindmarch said, wishing CHB all the best next season.
He wasn't sure of returning with the pressure of finding a paying job. "I need to get a different career if cricket isn't going to be the one.
"A lot depends on how the summer goes at home," he said, hoping to secure a country contract, otherwise studying to be a school teacher or a strength-conditioning coach.
