If you take the stats into account in ODI, Tim Southee never had a great performance against India in my memory and even if you check his economy against India is well over 6.15 but on the other hand Trent Boult does bowl well against India and even in a hypothetical situation with the form the Indian batsmen were in, i doubt they could have made any difference.
That may be true. But given how poorly the New Zealand pacers performed (especially Tickner, Duffy and Shipley), I think Boult or Southee would have performed far better. Lockie Ferguson was the only bowler who held his nerves against India. Anyway, the pitches were very unsupportive for the pace bowlers and therefore even the experienced bowlers would have struggled. On top of that, New Zealand is not a team with depth in their player strength, unlike the case with India, Australia or England. If 2-3 if their main players are unavailable, that will impact their performance.
New Zealand is currently certainly not as strong as the other three big teams. They are suddenly lacking behind. And I have to mention one thing which is the games being played in India are obviously going to be beneficial for India.
I am not going to say that New Zealand is not capable of winning against India. Currently, I am going to say that New Zealand lost because they simply did not play well enough and wasn't able to hold their nerve. And New Zealand knows very well that the track is favoring the batting side. So, if they can somehow keep wickets in hand, the runs will come. But they could not do that as well.