I don't think many would suggest BAR was the second best car in 2004 which was the other point I was making. Jenson had a great year and hauled BAR to 2nd in the constructors championship without a great deal of help from his teammate.
I don't want to labour the point, because much of what you say I agree with completely, but I didn't see 2004 as being such a fantastic season as all that. He was outqualified by Sato seven times for a start. He undoubtedly got some good results and showed impressive consistency, but no better than other apparent midfielders suddenly presented with a good car - e.g. Frentzen at Jordan in 1999 - and while many doubtless disagreed, my impression then was that many thought that (Frentzen) was about Jenson's level.
Certainly it was uncharacteristic of BAR to produce a good car, but that was more down to the tribulations of Williams with their walrus nose and McLaren with their dreadfully unreliable and slow car evolved from the unraced MP4-18. He was more often in front of than behind Alonso's Renault on the grid, and Button is not a noted qualifier.