For what I know, credits and synergy are created for the whole team depending on the time of mission completion, the objectives and the kills. And then it is shared between everyone in the team proportionally at your efficiency. So yes, global efficiency is not important, what is important is the relative efficiency to your team mates.
Here’s my last battle as an example:
TEAM 1:
PLAYER SHIPS FLOWN K AD AB D Obj DAMAGE TEAM % HEALS EFF REDITS
CorsarTM Templar 1 4 0 3 0 24,672 11.31% 5,685 452 61,824
daikr Dvergr,Stiletto 1 1 0 3 0 30,070 13.79% 0 108 31,388
Darkszz Alligator-M,Dwarf 2,Stiletto 0 3 2 4 0 23,026 10.56% 5,138 436 92,307
GenriPlotter Deimos 0 2 0 3 0 8,528 3.91% 0 183 40,514
nidheg Phobos 3 3 0 3 0 78,800 36.14% 9,519 859 86,656
NormanBates Machete AE 2 3 1 3 0 48,066 22.04% 0 109 58,249
polarchik Katana 1 2 0 2 1 4,886 2.24% 0 737 84,580
TEAM 2:
PLAYER SHIPS FLOWN K AD AB D Obj DAMAGE TEAM % HEALS EFF CREDITS
Acemenu Hawk-M 0 1 0 2 3 1,853 0.61% 0 1,617 153,148
Comrade92 Phobos 8 3 0 1 0 76,630 25.20% 0 1,041 78,894
konvic21 Steel Harpy 0 3 0 0 0 32,301 10.62% 0 346 59,718
LaenZero Wolf,Stiletto AE 0 4 0 2 0 9,057 2.98% 622 530 80,965
RestRing Alligator-M 4 7 2 3 0 67,919 22.34% 11,105 961 91,761
Snib Silent Fox 5 9 2 0 0 86,577 28.48% 0 1,502 82,997
TangoAlpha Hydra 2 4 4 4 0 0 29,705 9.77% 28,966 665 58,593
As you can see, there is no direct proportional relation between efficiency and credits. Don’t forget some people are licensed for double credit rewards.
And as you can also see, the players on the losing team earned basically the same amount of credits as the players on the winning team. That was my point.