I understand Yadav did bad and gave extra runs in his first spell but that does not mean that he will do bad in the death overs. He is capable of delivering yorkers, slowers, bouncers and in this kind of situation a fast or medium fast bowler is very effective than a spinner.
If you take CSK as example then you will see, Dhoni never ask Tahir or Harbhajan to bowl in this kind of situation. This is where Dhoni is great. He knows how to use his players and bring the best from them. Kohli is a stupid big head pathetic nut. He is a good batsman no doubt but his captaincy has big question.
Now, you can ask me then how do he manage with the Indian team? Well if you look closely then you will see Dhoni always makes the decision or gives Kohli the sign of the next move. Kohli really needs to learn captaincy while Dhoni is around.
I don't think that the verdict would change if he would have used any of these fast bowlers which is why he tried something different with Negi.