Last November, L.A. Times' reporter Richard B. Schmitt investigated this issue further (story here) and wrote the following:
The processing and evaluation of these cases takes significant time, and in many cases, several years. [The] Department is aware of the staffing needs to process the increase in clemency petitions and is working to address this ... the Department will continue to evaluate the staffing needs of the officeSchmitt also found that an additional staff attorney had been recently assigned to the Office of the Pardon Attorney. Finally, his article noted that the Department "routinely" sends clemency recommendations to the White House.
Today, an editorial in the New York Times informs us that U.S. Pardon Attorney, Roger Adams, recently submitted an "abrupt resignation." The editorial observes that a Justice Department investigation charges that Adams made "highly innapprotpate" racial remarks about a petitioner and threatened "retaliation" against employees who "complained" about his work. It is notable, of course, that Adams' resignation is first announced in a Times editorial (contra a "news" item). But today's piece also informs us that, at least once, Adams requested a larger staff to handle the clemency backlog. See the full editorial here.