The Volts won 10 consecutive games to win the title last season and that momentum almost carried the side into the semifinals of the Champions League in India.
That success was built on the back of an attacking brand of cricket which was in stark contrast with Otago's efforts in Saturday night's final at Seddon Park in Hamilton.
Having elected to bat, Otago made an uncharacteristically timid beginning and struggled to lift the run rate. Regular wickets snuffed out any momentum the side was able to build.
''We got tipped up by perhaps not being ourselves with the bat,'' Johnson said.
''We probably underachieved in terms of the score. I thought it was probably a 160-165 wicket. We were a little bit shy of that.''
Otago posted a relatively small total of 143 for five. Neil Broom top-scored with 44 from 38 but holed out at a crucial time.
Overseas professional Ryan ten Doeschate (36 from 24) whacked two sixes early and looked as if he might be able to rescue the innings and guide the side through to a more competitive score.
But he came unstuck when he miscued a drive off the bowling of the veteran Scott Styris. The 38-year-old bowled a frugal four over spell, taking one for 16.
Northern celebrated ten Doeschate's wicket almost as vociferously as it did winning the match. He was the key man in the line-up, and with him out of the way the home side had taken a firm grip on the game.
''Once we lost Tendo [ten Doeschate] we were struggling to get anywhere, really,'' Johnson said.
Earlier, he had sent fellow import Jason Holder in at No 5, with a licence to lash the ball to all parts. He was bowled defending and, from a brief glimpse, looked more suited to No 11.
The West Indies seamer was controversially brought into the side just for the final and forced Neil Wagner out of the starting XI and Sam Wells out of the 12.
Holder took two wickets in his opening over but otherwise failed to justify his place in the side. He dropped a sitter when BJ Watling was on eight and conceded 31 runs in his last two overs.
As far as experiments go, it was an epic fail. Had Wells been in the line-up, Otago might have batted with more assurance at the top. Instead the batsmen were tentative and batted as if they needed to shield the middle order.
Holder's inclusion changed the mix of the side but Johnson said the decision was made with the bigger picture in mind.
''If we had won, we would have had another option for the Champions League and that is basically what bringing a player in late in the piece is all about.''
While Northern was set a modest victory target, early setbacks meant the game remained in the balance for a long time.
Having slumped to 24 for three, Watling (37 from 30) and Daryl Mitchell combined in a valuable 57-run partnership.
Otago had chances to put Northern under more pressure but dropped crucial catches. Derek de Boorder grassed a regulation catch behind the stumps.
In the end Mitchell's patient and undefeated 46 from 42 proved the difference and a brilliant cameo from ScottKuggeleijn completed the five-wicket win.
Kuggeleijn whacked 22 from just seven deliveries and smote Holder down the ground for six to seal the win.
''We fought and fought with the ball and tried to screw them down. But in the end, we just didn't have enough up our sleeves. It is really disappointing but I'm proud of what the guys have done in this campaign. We just fell at the last hurdle basically,'' Johnson said.
