The crystallization of Fe-Co-B metallic glass has been analyzed using the novel approach to determine the continuous distributions of process rates in isothermal transitions. The analysis has allowed to determine the true activation energies controlling crystallization and their distribution as well as the values of the preexponential factor. Furthermore, temperature dependence of activation energies has been estimated and has been correlated with the data on nucleation and the crystal grain sizes determined from extensive quantitative transmission electron microscopy analysis. The information content obtained using the novel approach is compared and discussed with respect to the distribution of process rates active at selected times. Prediction potential of the novel approach for the long-term low-temperature stability of metallic glasses using the information on temperature dependence of activation energies is confronted with predictions from classical kinetic analysis.