The whistle blower submitted a formal complaint. The complaint matched the transcript of the phone call almost exactly.
But the transcript of the call didn't implicate Trump in asking for a political favour in return for aid, merely in the investigation of a currupt individual (who just happens to be the son of the Democratic front runner...).
Essentially after Russiagate flopped hard, they had to come up with a plan B, and this is it, an absolute waste of time.