How to Choose Slot Corner and Sub LB?

This is my first year of Madden. How do I determine who is the best to put at slot corner and sub linebacker? What do you look for when making that decision?

On slot corner you want them to be just as good as the other corners, but it’s fine if they are a little smaller but on the outside corners you want over 6 ft. Sub lb you want height and speed and lurker if your using a linebacker.