The head of Warner Music Group’s (NYSE: WMG) aggressive digital music strategy is leaving, according to the Wall Street Journal. Alejandro Zubillaga, a brother-in-law of WMG Chairman Edgar Bronfman, Jr., has been EVP-digital strategy and business development for nearly four years; he will step down June 1 and hand the role to his deputy, Michael Nash. Zubillaga told WSJ: “I’ve sort of fulfilled what I came to do at Warner.” Zubillaga said he’s likely to return to entrepreneurial investment work.

Since Bronfman and his group acquired WMG from Time Warner (NYSE: TWX), digital sales have increased steadily to become a significant part of the company’s revenue—14 percent in the last quarter. WMG has sold bundled albums on iTunes, made the first licensing agreement with YouTube (including a stake) and numerous other licensing deals, pushed mobile, etc. But it hasn’t been enough to make up for falling CD sales, slowing mobile sales and other issues facing the music industry. WMG presents a stark example of the industry’s woes. Acquired in 2003 for $2.6 billion, WMG’s stock closed Friday at $5.66 per share—a market cap of $846.29 million.

• Earnings: WMG Execs: ‘Smaller Scale’ M&A; Imeem Investment; DRM-Free MP3s
• Earnings: WMG Ups Digital 41 Percent Annually; Records Loss In ‘Challenging’ Year