Bangladeshi batsmen's performance is not consistent so they have been defeated. The pitch cannot be blamed. The pitch in this series is good enough. Bigger than that, Bangladesh is accustomed to playing on such a pitch. They know what the pitch is like. Even then their performance was dismal.
The pitch has received a lot of blame, because it was tailormade for the Bangladeshi players. Unfortunately the next two matches are also scheduled to be played at the Sher-e-Bangla National Stadium at Mirpur and I don't expect any improvement in ground conditions. The good news for New Zealand is that now their players (both the batsmen and the bowlers) have got adjusted to the conditions, as seen from the exceptional performance by Ajaz Patel and Cole McConchie during the third T20I match. The remaining two matches can go either way.
A good overall performance by the NZ team. Bangladesh lost because their batsmen were not able to face the Kiwi bowlers. Two more matches are left. Bangladesh is already leading 2-1 and I expect the next match might be won by the Bangladesh team. If they win then they will win the tournament.