a defense got better or worse when a certain player was on the floor when we can just decide who the best is by the number of positions they can guard?

Let's not look at who was on the All-NBA defensive team more times. Yes Rodman finished 1st in the defensive player of the year voting twice to Michael's once. But Michael finished 2nd another year, 3rd another and 4th yet another. Michael Jordan was an absolute lock down defender.

So since you discounted my stat (the number of points the team allowed when Michael/Rodman were in the game compared to when they were not) what stat would you use to prove Rodman is better?

To me it is all about the points given up, but if you want to go steals (no contest Jordan has triple the steals per game than Rodman did) or blocks (again Jordan wins this battle) feel free.