Exxon, as a prudent operator would have taken an analogue, like the Eagle Ford and used the worst case scenario. This would have gotten them about 42 MPa at depth. Instead it was 50 MPa. This is what can happen on an exploration well, since by definition, you don't know what you will find. What you don't do is assume that it will be one of the most overpressured reservoirs in the world and spend a whole bunch of extra money.
The offsetting wells are Olivio1, which tested 5000 bbls/d of 14 API oil from an unstimulated 1500 m of Hz. This well was in the La Luna and has produced more than 600,000 bbls to date. The second well is the Catalina 1, which tested at over 11,000 boed from an unstimulated 300 m Hz. It produced over 600,000 boe in about 2 years. This well was in the Rosa Blanca. They were both drilled underbalanced by Harken in the mid 90's. most of this info was in a previous CNE presentation. These wells are at the south end of the block immediately north of the CNE/Exxon property.
Finally, as far as the market is concerned, if you have read thousands of news releases and missed ALL the important information, imagine the poor guys who don't know as much as you.