[Tom Line]

Maneuverability - i.e. turning rate, is base on several things.

Torque (inversely proportional to speed), especially if you are skid-steering.

Friction, i.e. wheel material type.

Weight distribution front to back.

Wheel base, both in the x and y dimensions. "Rocking" your wheels, or lowering the center one, is a way of giving yourself a wide wheelbase because you generally only have 4 wheels that are primary load balancing wheels.

If you are looking at ways to improve your turning, ask yourself this:
Assuming that your torque is fixed,

1. Do we need friction on the front and rear wheels? Some people add zip ties around the wheels to lower it. Some people "flip" their treads. Some people use omnis in the front and rear. Some people use wedgetop rather than roughtop.

2. Is our weight distributed in the center of the robot? If you are weighted heavily to the front or back, it will affect how you turn. The easiest way to experiement is try with your battery in different locations and see how the robot reacts.

It's my guess that they either have more rock than you do, a different weight distribution, or less friction on their front and rear wheels.

Editted to add: I am by no means an expert on this - we've fought our own battle this year. We want straight line stability for autonomous, but it doesn't lend itself to easy turning. We went through a number of iterations this year with our drivetrain trying to find something that worked well. In the end we had to gear down more than we like just to be able to turn, and our top end speed suffered a bit as a result. We never did get that 5th auton line.