The walking partner tennis ball toss crossover basketball drill is a really good way to work on your ball handling, and also your hand eye coordination. If a player is having trouble keeping their eyes up on the dribble, this basketball drill will help force them to keep their eyes up. The reason that it will do this is because they will have to see the tennis ball toss coming at them.
Being able to see the floor while dribbling the basketball is really important for primary ball handlers. If you are not able to dribble with your eyes up you won't be able to read the defense, and see open teammates. This is also a great drill for non ball handlers as well, because it will help to work on developing soft hands.