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tokens: that the ejected metals are preferentially reincorporated back into galaxies from the circumgalactic medium (CGM). Li et al. ( 2010 ) essentially adopt this type of idea in their SAM by adopting a route to recycle most of the metals produced in newly formed stars through the hot phase. In their model, 95% of newly produced metals are deposited directly into the hot gas for galaxies with a dark-matter halo virial mass less than 5 × 10 10 M ⊙ . The metals then eventually fall back to the galaxy and fuel the next episode of star formation, resulting in a shallow metallicity−luminosity relation. Furthermore, the ejective feedback has other uncertainties that can affect predictions for low-mass galaxies. Henriques et al. ( 2013 , 2015 ) showed that when the outflowed mass has a long delay before being reincorporated into low-mass halos, the model can match the evolution of the field galaxy luminosity function remarkably well. Hou et al. ( 2016 ) demonstrated a model where the mass-loading factor decreases with time, as suggested by a recent hydrodynamic simulation (Muratov et al. 2015 ). Together with saturated outflows at the low-mass end and a strong local reionization, which are effectively similar to our extended model, the model (named “EvoFb-LR” in Hou et al. 2016 ) can achieve a reasonable fit to both the SMF and MZR of MW dwarf galaxies. While these prescriptions for outflow and reincorporation have been tested by recent hydrodynamical simulations, the actual behavior of the outflow is still a matter of active debate (e.g., Anglés-Alcázar et al. 2016 ; Christensen et al. 2016 ). We note the important caveat that tidal effects from the MW-mass stellar disk can reduce the number of surviving subhalos (e.g., Zolotov et al. 2012 ; Wetzel et al. 2016 ; Zhu et al. 2016 ), which can affect how the ejective model fits the stellar mass function. We stress, however, that the MZR is independent from the satellite abundance. Therefore, the requirement for weaker outflow implied by this relation is robust, even if a fraction of subhalos are destroyed by the MW disk. Still, it is clear that there is some degeneracy between the preventive feedback and the destruction of subhalos. To break this degeneracy, detailed modeling of these processes and quantitative inferences from dwarf galaxies both within and outside the MW will be essential. Although the model presented here with the addition of preventive feedback can match the data, the physical mechanisms that produce the prevention remain unclear. We have taken an extreme model where baryons are prevented from collapsing into low-mass halos, but the assumption has not been fully tested against observation. At the current stage, other alternative hypotheses, where baryons still make it into the galaxy but are prevented from forming stars by large turbulent pressure or photoheating (e.g., Forbes et al. 2016 ), can produce similar effects in galaxy formation models. The data constraints adopted in this