I love ppl who love to jump into discussion without first knowing what the orgininal argument is.
First, your calculation is fairly close the actual results but you misunderstood the orginal argument.
Let's do a quick recap - Aurik argue that Lars make significant contribution to BST damage output by stating:
Last party I had with Solsovly, his Lars put up 5.5% against a maxed out ridill/purpleberk war + maxed out usukane/relic mnk, with brd+cor buffs that Lars doesn't get. In a more NQ party, that would be easily 10%.
What I am trying to point out is quoting Lars performance by percentage in a 3 DD party does not give a valid result since the numberof each individual DD is exaggerated including Lars itself. As in this case, Lars DD output increases from around 4.03% to 5.5% by simply switching to a 3 DD party.