Stokes and wicketkeeper-batsman Jos Buttler were both allowed to miss England's three-match ODI series against Ireland but have been recalled by the ECB to join a training camp in Spain.
"I think it's pathetic. An absolute shambles," cricket.com.au quoted Pietersen as saying of ECB's decision.
"Stokes should be playing in the semi-final, and the final. The last week of the IPL is a huge occasion."
"What are they going to Spain for? To field a couple of balls?" said Pietersen.
"He should be playing in the IPL. Just speak to him, speak to Jos Buttler, they'll talk about how much it has helped their development being out there," he added.
The 25-year-old did justice to his selection as he starred with both ball and bat, scoring over 300 runs - including a sensational century - and taking 12 wickets.
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