Offline
That's simply not true. If they both have their positives and negatives, who you go with isn't always obvious. That's true with a lot of things. Making decisions like this isn't an exact science, and if they're close, you give consideration to both.
That said, I tend to think it's more about not tipping off the opponent as to who you're starting. There's not a big difference between the 2, but I think you have more game film on Rattler, so the defense would have a better idea how to defend him than Haener who has a more limited body of work to pick apart.
It might not be obvious, but you need to make a decision so you can get that guy all the reps in practice and so KK can design the game plan around him. Instead they are splitting snaps and KK is either making two game plans or one that kind of fits both of them. Either way, it isn't ideal.
So, if they are really that close pick one for this week and give the other one a start next week.