The Polish pianist Rafal Blechacz suspected nothing when, while preparing for three concerts in Switzerland in late 2012, he was bombarded with questions by the artistic director of the Lucerne Symphony Orchestra. He had no clue that a recital he gave that year in Schenectady, N.Y., was closely scrutinized and discussed and debated by a select few listeners.

And he thought nothing of it when the man from the Irving S. Gilmore International Keyboard Festival in Kalamazoo, Mich., sought a meeting in Berlin, assuming that they would simply be discussing his next appearance at the festival.

Instead, it was in that meeting in Berlin last summer that a startled Mr. Blechacz learned that he had been selected to receive one of the great windfalls of the music world: the $300,000 Gilmore Artist Award, which is given every four years to an unsuspecting pianist deemed worthy of a great career by a panel of anonymous judges who conduct their worldwide talent search in secret.

“I was lucky,” Mr. Blechacz said of that Berlin meeting, “because I was sitting.”

The award, which will be announced officially on Wednesday, is often thought of as the music world’s version of the MacArthur Foundation’s “genius” grants: a prestigious prize that cannot be applied for or sought. The long confidential selection process aims to judge pianists over a sustained period of time, in marked contrast to hundreds of other sink-or-swim piano competitions that can resemble beauty pageants or reality shows.