There are multiple factors that affect the points you get at the end of the match. The better you perform the more points you get.
Your match performance is calculated based on the data available on the Detailed Statistics page (your screenshot). Travel distance, survival time, restored health, assists, rescues and the supplies you find count towards your performance.
Please also note that you will start getting less points each time you move to a higher tier. If your friend is higher ranked than you, that could explain why he got a minus.