I assume that most teams are trying to pick up the balls and bring them into their robot, possibly with some sort of sweeper/ball magnet. Our team was just having this debate, so we wanted to see what the Chief Delphi community thinks. One sweeper? Two sweepers, maybe with one in the front and one in the back? Or none at all?
One. You can only hold three balls at a time, so being able to pick up from so many directions really isn’t necessary this game.
Then again, It hasn’t been played yet, so I may be wrong.
Just my $0.02
I’m not going to give away too much, but consider this: You don’t need any more than one ball magnet for whatever amount of ball intakes you have.
I think you are only allowed to have one break in your bumper perimeter. So I don’t think you could have a sweeper on the front and back of the bot.
Who says it needs to be outside the frame perimeter? 
Could you please provide a rule or Q&A ruling for this statement?