''Not enough runs and also we weren't able to get any sustained period of pressure, which brought wickets," McCullum said of New Zealand's shortcomings in Napier.
''Par was probably 290, and we did okay to get to 270. It was a very defendable total, but you needed things to go your way on a very good wicket."
That said, Eden Park ''should be amazing. It's set up beautifully and the way the series has gone - win one, lose one, win one -- it would be quite nice to lift the trophy."
McCullum is seeing the ball like a pumpkin and blazed 74 in just 36 balls to pull New Zealand up to a respectable total with the man he replaced as national captain Ross Taylor.
The pair laced the England attack, putting on 100 in only 54 balls for the fifth wicket, Taylor finding his form after a lowkey return to the team, hitting his seventh ODI ton, 100 off 117 balls.
However the lower order failed to fire, and the last six wickets went down for just 26 runs in 25 balls. It could have been a seriously challenging target of about 300; instead England, batting sensibly - and in 22-year-old Root's case, 79 not out off 56 balls, with plenty of panache - did a thoroughly professional job.
McCullum never doubted Taylor would regain his touch.
''I'm really pleased he managed to get a score. I thought he played really smart through the innings.
''We all knew Ross would get runs at some point. He's a high class player. It certainly wasn't a matter of hoping he was going to get runs; it was a matter of when it was going to happen."
England's leading bowler, Jimmy Anderson, took five for 34 and his work with Steven Finn in the first 12 overs of New Zealand's innings was highly impressive. It put New Zealand on the back foot and, even allowing for McCullum and Taylor's efforts, England always held the whip hand from that point.
Cook reckoned it the best opening 12 overs he'd could remember. He was delighted the way his team bounced back from defeat in the series opener in Hamilton last weekend.
McCullum has been a challenge for England's bowlers and Cook spoke highly of his contribution.
''He's a very dangerous player, no doubt about that," Cook said.
''He hits the ball, not in strange places, but very long and no ground is really big enough for him."
That said, Cook felt England had bowled better to McCullum last night than when he made his match-winning 69 at Hamilton.
''He was hitting the ball in areas he wasn't quite so comfortable hitting. Fair play to him, it was a great little knock and he got them up to a defendable total."
