According to the ring it was. Armstrong went 27-0 that year, 26 of those wins by knockout. One of those was a KO of Petey Sarron for the world's featherweight title, the first plate of the triple crown. Which other fighters, and which year, could be considered for this accolade, the greatest year of any fighter, ever? Or perhaps you agree that it's Armstrong in 37?
I tend to think more of the year Armstrong had in '38, because he was no longer a contender best avoided, but a champion himself, and therefore possessed what his opponents coveted. Anyhow, that's my perspective, for whatever it's worth.