Storm lance damage number is wrong

For a frenzy charged empowered storm lance, theoretically (level 20) the damage has 3 stages
1. Proj Hit (187%)
2. Frenzy charged bolt (91%) every 0.2s out of total duration of 1.5s, so it should hits 7 times (637%)
3. Detonation (405%) fire 16s bolts (total of 6480%)
Adding up to a total of 7304%

Based on Frame to Frame analysis compare to auto attack vs boss w/o resistances, the frenzy charged storm lance is doing about 1860%. That is 74.5% less damage then written in description.

Based on Poison on hit with unique spear having unlimited poison, one frenzy charged storm lance is hitting 17-18 times ( in theory should be 69 times). So it is unclear why in default 75% of hits won't hit the same enemy.