SAP CEO Bill McDermott announced he was stepping down last night after a decade at the helm in an announcement that shocked many. It’s always tough to measure the performance of an enterprise leader when he or she leaves. Some people look at stock price over their tenure. Some at culture. Some at the acquisitions made. Whatever the measure, it will be up to the new co-CEOs Jennifer Morgan and Christian Klein to put their own mark on the company.

What form that will take remains to be seen. McDermott’s tenure ended without much warning, but it also happened against a wider backdrop that includes other top executives and board members leaving the company over the last year, an activist investor coming on board and some controversial licensing changes in recent years.

Why now?

The timing certainly felt sudden. McDermott, who was interviewed at TechCrunch Sessions: Enterprise last month sounded more like a man who was fully engaged in the job, not one ready to leave, but a month later he’s gone.

But as McDermott told our own Frederic Lardinois last night, after 10 years, it seemed like the right time to leave. “The consensus was 10 years is about the right amount of time for a CEO because you’ve accomplished a lot of things if you did the job well, but you certainly didn’t stay too long. And if you did really well, you had a fantastic success plan,” he said in the interview.

There is no reason to doubt that, but you should at least look at context and get a sense of what has been going in the company. As the new co-CEOs take over for McDermott, several other executives including SAP SuccessFactors COO Brigette McInnis-Day, Robert Enslin, president of its cloud business and a board member, CTO Björn Goerke and Bernd Leukert, a member of the executive board have all left this year.