I'm absolutely sure that people gonna start coming for me on this but I'm going to say it anyway.
When you see that batsmen are going for runs in the death, you ought to finish off the overs of an inexperienced bowler like Harshal Patel and move your best bowlers Bhuvi and Bumrah in death. This is coming from a hardcore RCB fan. Harshal Patel tend to panic and he has those days where he won't perform, it was quite evident in his first spell itself.
That was the worst decision made by the captain. And yes, Kohli was heavily criticised for such acts in his captaincy. Finishing off experienced bowlers ahead of Harshal Patel and just like some of you pointed out, Patel might just have screwed up his chances for next series or probably T20 world cup too. It is different thing that you didn't have an option in previous matches. It was okay to use him in absence of experienced players. But when you have world's best bowlers in the lineup, use them judiciously.