In recent years it has become apparent that unitarity and causality of QFT dramatically constrain the allowed space of consistent IR dynamics. In this talk I present how the electroweak parameters are constrained due to the particular structure of universal theories,  a broad class of well-motivated microscopic dynamics of the electroweak sector that go beyond the Standard Model description. In particular, the W and Y parameters are constrained to be positive by unitarity and are necessarily the leading effects at low energies. I discuss how this observation affects the interpretation of current data and assess the impact of future constraints.