Right now if you partake in a match - regardless of skill - you get credits. Simple as.
Such a baseline reward system has resulted in players simply rigging up rubber bands to their analogue sticks (thereby keeping their character constantly moving) to rack up the points. You can assume the idea of a "fixed amount no matter what" was put in to help newcomers or more amateurish players, as by having a certain figure releasing per match, there's always some level of progression guaranteed.
However, within this method is a complete lack of incentive to play well. Yes, you can focus on the objective to get more points faster (which will have a minuscule effect on your post-match credit total), but say you get 20 kills and the next guy gets 2 - you'll both get the same credits.
Now, first of all, Battlefront 2's post-match screen needs an animation to shows how Battle Points become Credits, as right now it's very hard to know what you did well or need to focus on.
Alongside, tweak the algorithm so your in-game Battle Points convert into an additional amount of Credits. As your total BP is predicated on everything from kills to playing the objective - even damaging players from afar - having this result in tangible currency would encourage players to do their best every time.