I think you're spot on in terms of when he 'mattered the most' between Blackwell and Groves, there was still a 'mistique' about how good he could be. Groves totally exposed him.
He impressed in the Yildrim fight, we didn't really know Yildrims level at the time though. Which made Eubank look better than he actually was. His fight against Billy Joe was maybe his most impressive though. He only lost that fight because he started slowly.