Additionally the tracking the aircraft took was not as direct as could have been, would have been wiser to request direct tracking to final approach for bk, and when approaching abeam RIC, after assessing performance output of the aircraft vs wx decision to continue or a turn onto the ILS as appropriate. I think if the remaining engine had a problem he also would have reported it so and as stated by krusty the ground speeds and rates of descent are fairly conclusive to the aircraft not being at vyse and the pilot descending to conform to ATC requests, anticipating the performance of his ship to be sufficient. Unfortunately bottom of descent is the worst place to find out where you stand performance wise.