From the article:

Wallace came to the center’s attention years ago, largely through the endorsement of writer DeLillo, whose papers were acquired by the Ransom in 2004.

“Wallace idolized DeLillo, and DeLillo thought of him as one of the really promising young American writers, so we thought we better look into it,” Staley said.

The center sent Wallace a letter while he was still alive inquiring about his papers, “but he never replied,” said Megan Barnard, the deputy director for administration and acquisitions.

In early 2009, Wallace’s estate approached the Ransom , which acquired the material in December. Officials declined to discuss the mechanics of the deal or the price.

Normally, such a large amount of work would require more than a year of archiving and processing, but the Wallace papers will be available to researchers and the public in the fall.

I did read his essay on Federer, though. But I do remember learned_hand’s one and only fanpost dedicated to him after he died.