It looks like the U.S.'s oldest business school has lost some of its luster lately.

Following a rather unflattering Wall Street Journal article about a sharp drop in applicants, the University of Pennsylvania's prestigious Wharton School of Business said Wednesday that its admissions director, Ankur Kumar, is resigning effective Friday.

Applications for Wharton's MBA program have dropped about 17 percent in the last five years, says John A. Byrne at Business Insider. Last year the school received just 6,036 submissions — compare that to Harvard Business School, which got almost 10,000.

Meanwhile, in the past decade or so, the school's ranking on various MBA program lists has started to slide as well. After six years on top of Businessweek's semiannual top MBA ranking, Wharton was replaced in 2000 by Northwestern's Kellogg School of Management. Then in 2006, University of Chicago's Booth School took top billing. Other similar lists have Wharton fourth, after Harvard, Stanford, and Chicago.

Wharton says the drop in applicants is actually a good sign, claiming "the school is doing a better job at targeting candidates." It may have a point: The most recent class's average GMAT score is 725 — the second-highest of any school in the world, says Byrne. And last year, the post-graduation job placement rate was one of the highest in the school's history. Three months after graduation, 97.8 percent of the class had jobs.

But that doesn't change the fact that fewer people chasing M.B.A.s want to go to Wharton. Here are three theories why:

The recession
The drop in applications might be a result of students shifting their interest "from finance to technology and entrepreneurship," says The Wall Street Journal, which may be a side effect of the financial crisis.

Wharton over the past century built its reputation as a training ground for Wall Street titans, but the financial crisis closed off many paths to such careers. The school in the mid-2000s regularly sent more than a quarter of its students to jobs at investment banks and brokerage firms. That figure has slid into the teens. [The Wall Street Journal]

Other schools have spent recent years "strengthening their ties to tech companies," says The Journal. And U.S. News ranked both Stanford and Harvard's entrepreneurship programs higher than Wharton's.

Awkward group interviews
Wharton's soon to be ex-admissions director, Ankur Kumar, told Bloomberg Businessweek that the drop may have more to do with new group-based admissions interviews the school started last year. The interview involves "applicants meeting in small groups to work as a team to solve a business problem," says Bloomberg Businessweek, and "may have discouraged some applicants, although Wharton has not indicated it plans to abandon the new process."

The interviews may be particularly discouraging for applicants who speak English as a second language, says Byrne.

All the deck-shuffling
Finally, Wharton seems to have a leadership problem — a possible red flag for a school that's supposed to be a training ground for leaders.

"The school has had four admission directors in the past decade," says the Journal. "Ms. Kumar's counterparts at Harvard and Stanford have been at their schools for more than a decade." That could make it "tough to get chemistry and an overarching strategy," a former Wharton admissions officer told the paper.