Mebanes own fund GMOM has underperformed even a conservative benchmark since inception. https://www.cambriafunds.com/assets/docs/GMOM-FactSheet.pdf
I see that someone has tried to make the case using that paper and some updated ones for a TAA model going back to 1970. Extrategic Dashboard - Faber Tactical Asset Allocation w/ Relative Strength (Updated)
But they bench it against the S&P 500 and not a 60/40 portfolio or something more relevant.
I think the core idea is pretty basic.