The theory they’re talking about is not just curve fitting. Instead only pieces which match the physics of QCD / the Standard Model Are included. It is simple

The theory they’re talking about is not just curve fitting. Instead only pieces which match the physics of QCD / the Standard Model Are included. It is simple to write down terms that you might include in a “just make up enough terms until it fits” methods that are excluded based on the requirements of symmetry matching that the whole program of EFT is organized around.