Strong era and weak era knowledgebale posters, please help solve my dilemma. If Nadal had won the fifth set at Wimbledon 07, and had Djokovic converted those set points in USO 07, resulting in Nadal ending year number one...would 07 have been the strong era? Conversely, if Federer somehow won the two points he needed to win Wimbledon 08, thus remaining number one through to the end of the year....would that have made 08 part of the weak era? Would Nadal dominating FO 08 the way he did, make that a very weak era on clay compared on 05-07 when he was challenged a bit more? If not, wouldn't the same rules apply to Roger on the other surfaces between 04-07? Also is 09 part of the strong era or weak era? This bit is always grey. Or did the real strong era begin in '11 when Fedal era was officially over?