DBHF theory allows a quantitative prediction of nuclear saturation properties. The corresponding EoS of symmetric nuclear matter turns out to be soft at moderate and stiff at high densities, in agreement with constraints form heavy ion reactions. Saturation point, compression modulus and symmetry energy are predicted very close to the empirical values. The present DBHF calculations are based on improved projection techniques which allows a relaible determination of the momentum, density, and isospin dependence of optical potentials and nucleon effective masses. In particular, Landau and Dirac masses can be derived within the same approach. Doing so, the controversy between relativistic and nonrelativistic approaches concerning the proton-neutron mass splitting in asymmetric nuclear matter has been resolved.