From what I generally know this is called an Anabolic Prime and lasts for a few weeks. You half the protein you eat and raise the carbs after a 8-12weeks hard training cycle and high protein diet and do light/high rep training or not at all, so that you down-regulate anabolic hormones and receptor sites for androgens again. It kind of mimicing the same principles of anabolic/adrogen cycle. And basically that's the reason why most of the drug cycles last for 8-12 weeks because the effects of the drugs are dropping dramatically after that period(and this is true for both natural body hormones or injectables). So this is good for the natural trainer also,and as it seems the body adapts to a specific training schedule after 8-12 weeks, the end of an adapted training cycle perfectly matches the limitation of the body's resources for building muscles (hormones). It also helps to became sensitive to insulin again because a high protein diet combined with high carbs for a long time can make you insulin resistant,which is not good for building muscle and lose fat. It is important to consume enough fats on a high protein high carb diet to stay away from this as much as you can until the end of the cycle.
It is actually nothing new. It is just structured well in a book with given diet and training samples that's all.
I have found and downloaded Optimum Anabolics (not legally

shhhh....) and it's pretty solid I can say. Actually it is a 5star in the net.
But Mark's routine and diet philosophy of MANS is solid too and definately a 5star.And don't forget Mark's cycles last for 9 weeks plus 1 off where you can have your Prime. Mark actually is already using this principle. And MANS has the advantage that will not make you insulin resistant and the huge advantage of the carbups(since you drop protein intake and up the carbs you can call it Intra Cycle Anabolic Prime,but it's complete only if you do not workout during that day). It is different to carb-up when you do a high fat diet than an already high carb.
P.S: I am doing the GLAD diet which is 30% fat, a fairly good ratio for a high carb diet...