Back players almost always shoot off the break, shooting the lanes (where the opposing players will be by the time your paintballs reach the other end of the field).
Mid players can play like back or front, depending on the field, and the number of players.
Check out this video (paintball team I am on). We are a 3 man team.. all in our family. As you see, the far guy (me), runs and guns shooting the lanes, but I am very quick off the draw on the gun. The middle guy is my 16 year old who is slow off the draw, but shoots the lanes too. My wife (right hand player) does a unique run and gun effort :)
I hope this works for you. You might have to DL it.
Video
The field is Niagara paintball Games in Niagara Falls, Ontario
Link to NPG