Pietersen has gone back to England as they prepare for a home series against the West Indies. He had scored 305 runs from eight innings at an average of 61 with a strike rate of 147.34.
"When Kevin was there, he was performing really well for the Daredevils in the middle-order but now some other batsman needs to put his hand up and perform at his best," Pathan said at the post match press conference after Delhi lost by six wickets to Kolkata.
"We have some wonderful players in the middle order like Ross Taylor. Once he starts firing, you know he is a player to watch out for. He can hit the ball long way. We have no doubt with every match he plays, he is getting better.
"Kevin has done a good job for us but at the same time, it's an opportunity for others to take his place," he added.
Pathan said the loss of both the openers in quick succession and failure of the bowling unit led to team's defeat at the hands of KKR.
"We did not put enough runs on the board. We could have scored 160-plus but that wasn't the case today. We lost Virender Sehwag and David Warner around the same time and that put us on backfoot.
"As a bowling unit, we always try to get better with each passing game. We did not perform well and need to bowl better in matches ahead," he said. More
