The question you were afraid to ask is answered here.
In CMBS 1.0, also known as legacy CMBS, payments of interest are senior to payments of principal. Thus, when a deal had shortfalls due to delinquency and there was a sale of property which did not result in loan liquidation (e.g. Beacon Seattle in GECMC 2007-C1, or West Hartford Portfolio in BACM 2007-5), proceeds would be applied to paying off prior interest shortfalls in lower-rated classes rather than being applied to paying down principal in the front-pay higher-rated classes.
Understandably, this got AAA investors upset. Why were lower-rated bonds receiving any sort of cashflow when they were not? What were the ratings agencies thinking? Thus, in CMBS 2.0 starting with the JPMCC-initiated deals in 2009, all cashflow is directed at the senior-most classes. This means that if a class suffers an interest shortfall, that shortfall is permanent until that class becomes a front-pay and becomes eligible for recoveries.
What makes CMBS 3.0 any different? As far as I can tell, the difference is that 3.0 deals include an operating advisor (e.g. Pentlalpha) as a party to the transaction. The operating advisor does not seem to have any fiduciary role and seems to exist for the sole purpose of gathering fees as an advisor to the special servicer, but hey, we're all friends here so why not.
Can anyone shine more light on this? What do you think?