It would be nice if when you have an item in the ready column, if it was marked with having an upstream dependency that was not completed without having to open the backlog. Or even if V1 didn't allow you to move such an item to the implementation column due to that incomplete work. Or another method would be to change the color of the backlog item or even a little red, yellow, or green stop light icon on it to let you know it can be worked.