My multirange (1,2,3) budget beamer battleships ships cost half the minerals of some of my opponents range 3 expensive beamers.
Winning a beginner game is certainly achievement but it does not make you expert. There is huge difference.
Why i think it was beginner game? Your descriptions of fleets, their sizes and designs indicate it. Medium game ... so main guys have about 100K economies. You say these people are wielding CC-s, DD-s and morphs? About 100 BB battle was decisive? What?!? In medium game? Where went the 1000+ nubian fleets?