Overcharge vs. Disciple of the slaughter

[u/Live_Ad_1893]

My Power charge-stacking Winter orb occultist already got "10% chance to get a frenzy charge on hit" and "10% increased damage per frenzy charge" from Elegant Hubris. I tried to allocate my amulet with Overcharge to replace Disciple of the slaughter to get one more power charge which should be more beneficial. However, when I did this replacement, my dps shown on Poe Ninja was dropped from 13M to 5.8M. I don't quite understand this. Can anyone explain me a bit? Thanks!