Durability. It's different this year from years past; if you undertook basic design wisdom, your robot is probably safe from most aggression from other robots. This is no guarantee that you're safe from the field.
It took most of the Bayou regional for our two teams to find all the little things that fall apart when you go banzai over these bumps. If you've got a practice robot or used the withholding allowance to keep your drivetrain and you haven't built a bump, follow these steps:
Step 1: Build a bump. Go ahead, throw the carpet on it; reasonably close rugs can be had for $20 at Walmart.
Step 2: Run your robot over the bumps three ways:
This will shake out something that you didn't have to strap down quite as tight in years past. Fix it now rather than later.