  Different scenarios for modeling resonances in a thermal model description of
hadron yields measured in heavy-ion collisions are explored: the zero-width
approximation, the energy independent Breit-Wigner scheme, and the energy
dependent Breit-Wigner (eBW) scheme. Application of the eBW scheme leads to a
notable suppression in the proton yields, stemming mainly from a reduced
feeddown from $\Delta$ resonances because of the threshold effects. A
significantly improved agreement of thermal model with hadron yields measured
in Pb-Pb collisions at $\sqrt{s_{_{NN}}} = 2.76$ TeV by the ALICE collaboration
is obtained in the eBW scheme at $T \simeq 155$ MeV, indicating a possible
resolution of the so-called 'proton anomaly'. The results obtained show that
there are significant systematic uncertainties in the thermal model due to the
modeling of broad resonances.
