Keep in mind that the special effects of some legendaries are difficult to sim appropriately - or, indeed, to put in any concrete quantitative metric, as with the defensive value of Prydaz. Sephuz is also a special case as I do not believe the sims take into account its bonus effect, and there are several fights this tier where you can reliably trigger it.
Simcraft is a model, and it has its limitations. The preset scenarios are rudimentary at best and do not fully reflect the constellations encountered in real fights. Always keep that in mind, and apply some thought to the results. Admittedly, without concrete data it's quite difficult to make accurate determinations.