You can read more about Mark's approach and his thoughts about optimal decumulation strategies in his new website.
For those who wish to "drill-down" more into his research, I recommend that you look at his recent (January, 2014) Power Point Presentation in the section which describes his approach.
I worked with Mark when he was the Director of Retirement Research at Towers Watson. He is one bright guy. We wish Mark well in his new endeavor and look forward to more educational material on his website on the subject of optimal decumulation strategies.