66-19 is actually 47 more kills then deaths.
Also the patch wanted more "team" based rewards. from what i have found what everyone needs to do is find an armor setup that has the best balance of cost/survivability which will allow you to showcase your skills in the best way possible, while also helping your team to win rounds.
This becomes difficult with the banner balancing, but going 66-19 on siege and losing is going to be more an issue with you not leading your team and instead just farming kills. When i play siege ill go pretty even on k-d but at the same time, ill be in team chat giving out orders and trying to get people in the best position to win the game. Often times when attacking ill see people going up siege towers or trying to flank when the door is wide open for us to push through, often times they go the where they see easy kills.
When defending you will have people with full plate standing over a ladder with a bar mace killing noobs when the rest of the enemy team is pushing the flag that everyone else is trying to defend.
so TL:DR on siege k-d doesnt matter, being in the right position to help your team is what matters.
In battle its all about finding the other teams best players and killing them before they start rolling, does the other team have goretooth? your best player better be making a b-line right for him to stop him early.