BlackBerry (Nasdaq: BBRY), which is rebuilding its management team under new Chief Executive Officer John Chen, has hired SAP AG executive John Sims to run its global enterprise services.

Sims, who was president of SAP’s mobile-services unit, will join BlackBerry in January, the Waterloo, Ontario-based company said today in a statement. He also serves on the board and executive committee of CTIA, a trade group for the wireless industry.

In hiring Sims, Chen is drawing from his former employer, SAP, the German-based business-software giant. Chen was previously CEO of Sybase Inc., which was acquired by SAP in 2010 after he turned around the company. He aims to pull off a similar comeback at BlackBerry, which is reeling from years of losing market share to Apple and Google’s Android.

“The changes we are making demonstrate our commitment to innovating for current customers who count on BlackBerry,” Chen said in today’s statement. “John will be central to all of those efforts.”

The move follows the departure last month of BlackBerry Chief Financial Officer Brian Bidulka, Chief Marketing Officer Frank Boulben and Chief Operating Officer Kristian Tear. Chen was named to the CEO job on Nov. 4 after a failed attempt by its largest investor to sell the company for $4.7 billion.

Three more executives’ departures were disclosed Monday.

Mark Cameron, director of global public policy, is leaving to join public relations firm Hill & Knowlton, marking the latest executive departure for the struggling smartphone maker.

Rick Costanzo, BlackBerry’s chief of global sales, and Chris Wormald, its head of mergers and acquisitions, also are leaving the company, said Lisette Kwong, a BlackBerry spokeswoman.

[BlackBerry operates two research and development offices in Cary, N.C.]