Why your team lost...

In the decades I have playing BF games, there are also some really simple things that every player should do and if your team has more players that refuse to do these things, 99 out of 100 times your team will lose. 

1 - Spot All Enemies

2 - Be aware of your surroundings (don't just look forward at all times)

3 - stop running everywhere

4 - use vehicles and/or join them as gunners (or for a quick ride to an objective)

5 - don't stick to one class and one loadout the entire match (unless you are with a squad or on a team, where there are lots of players of each class and loadout)

6 - switch to AA or AT class at least ONCE per match (or more, when necessary)

7 - don't sit at a gun emplacement or in one position the entire match, even as a sniper

9 - squad leaders need to be marking objectives (if not, pass lead to someone who will)

10 - if Assault (or recon in other games), make use of your spawn beacon (and not miles away)

11 - use the environment (don't just run across a field in the open while being fired upon)

12 - if you can't survive more than 20-30 seconds in a vehicle, STOP DRIVING/PILOTING THEM!

13 - drop ammo and supply bags, medpacks, heal and revive others 

14 - use smoke and incend or special smoke/gas to block enemy and vehicle views

15 - every match, there needs to be at least a few sniper and several LMGs used for suppression 

16 - take an hour and learn about each map's tips and environments, which vehicles spawn for which modes and of course, learn the game modes

It's not a lot. It's really just common sense stuff, but so many teams lose because of any number of these. 

And of course, play the objective lol