IND vs BAN: If you are wondering why Akash Deep is so effective upfront despite bowling with a semi-new ball in Test cricket? First of all, looking at the way he has progressed so far he is easily the find of the season and looks good to replace Mohammed Shami.
He has impressed so much that he can even find a place in the playing XI even after Shami swings back into action.

Coincidentally, his action, especially the follow-through, is so much like Shami's. Like Shami, Akash has a skiddy action that allows him to generate movement off the pitch. His ability to maintain a tight seam position ensures that the ball grips the surface, creating seam movement even with a semi-new ball, which is crucial in Test conditions.
Akash also bowls at a pace similar to Shami's, often around the 140 km/h mark, but with greater emphasis on accuracy. He pitches the ball up to the batter and his control over line and length means he can consistently hit the right areas, making it difficult for batters to settle, especially in the early phase of their innings.
Even with a semi-new ball, Akash has shown an ability to get reverse swing, another trait reminiscent of Shami. This makes him a threat in the middle overs of an innings, as he can make the ball dart in or away from the batter, exploiting any slight unevenness in the pitch.
With the Indian team always looking for more and more pace bowling options, Akash's success on placid tracks like in India makes him a big contender for the Border-Gavaskar Trophy. Who knows? He could be sharing the new ball with Jasprit Bumrah, who was a touch short on the opening day of the Kanpur Test against Bangladesh.
Akash also has another strong point and that is to draw the batter onto the front foot so that the opponent gets less time to read his bowling. He could eventually become a force to reckon with like Shami. Who knows? If morning shows the day, Akash Deep's first spells are making the right noises!