Indeed, in a worst case scenario with a locked fan, say, not only is the drag well above the assumed levels resulting in badly degraded performance, but the drag is also increasing the control requirements even WITHOUT increasing the thrust, and it may in fact be impossible to square that circle. Some failures will not be survivable... no matter what you do with the thrust levers.
I would discount the locked fan scenario as not realistic or valid.
The drag characteristics are set by the inlet frontal area and not the engine fan where the spaces between blades are great enough to let the air out the by-pass. Engine spillage effects are only temporary in nature and typically associated with engine surge.
All this not withstanding flight simulator training.