Arshdeep Singh has frequently being benched under Gautam Gambhir management.
Though there is speculation that Arshdeep would play the final match of the series, Ashwin believes the left-arm pacer should be an untouchable figure in the fast-bowling unit.
When asked why Arshdeep was benched, the Indian team management responded that Harshit Rana and Prasidh Krishna required more match practice. However, Ashwin is opposed to the concept, believing that prolonged periods of warming the bench will cause Arshdeep to become 'rusty.'
"The contest is between the bowlers. For South Africa, you need a hit-the-deck bowler. Prasidh Krishna and Harshit Rana both need match experience, so I can understand the thinking. But no one is thinking about Arshdeep Singh, who will stand in his shoes and think? This is not about how much he has played and how much he hasn't played," Ashwin said on his YouTube channel.
"What must he be thinking right now? He has done so much, yet he is still fighting for his spot. Whenever he plays next, he will be rusty. No matter what you say, this is a game of confidence. Why does this happen to the bowlers at all times? It never happens with the batters," he added.
According to some, Arshdeep was benched for the first two games against New Zealand since he will be participating in the T20 World Cup, which begins on February 7.
However, since head coach Gautam Gambhir took over, Arshdeep hasn't been a reliable starter for India in the T20 format.
"I have been in this position, so I know how it is. This is why I am fighting for Arshdeep Singh. Whenever you have given him the ball, he has performed for you. Allow him to walk into the playing XI with his head held high. He deserves this, boss. Now people are saying he will play the third ODI. What is the point? He didn't play the first two ODIs, and why did that happen? What will that do to his confidence?" he added.
The third ODI between India and New Zealand will be played on January 18 in Indore as the series stands 1-1.