I think what it might be, is that there is an importance, to the notion of a "clean exit". A high board diver's score, is partially dependent on the quality of the exit they make into the water. If you make a mess of the exit, you lose points. So too with an Evolutionist, the whole point is that you want to make a transition to the optimum Creation - that is, you don't want to end up half one creature and half another, you want the optimum of one in particular. Now you might say "that's convenient", and in part you might be right, but think through what the preceding step must be: if you have an alternative, obstruction to that alternative is no longer a positive - as mutation is claimed to be!
The difficulty is that you need to prioritize different mutations in different ways, or you will end up applying mutations meant for an old design, to a new design, which a sound Evolutionist would counter needs a new mutation. That was Jesus' lesson, when He said "no one puts new wine in old wineskins" (lest the old wineskins break - gospels, from memory). Basically, old mutations slow progress through new mutations down, to breaking point. This is where the idea of a 'clean exit' comes in. If before you transition yourself to a new species, you slow down and empty yourself out of mutations (pertaining to the old design), and then make a transition to a new species, the new species will have all the advantages of being refined Evolutionarily speaking, but none of the hangbacks of the previous design. This is a clean exit - and it ought to score highly!
Now you might say "but how do you know how to pick between old and new mutations?" I think this is a great question. To the Creationist, this question is meaningless, because who they are, why they are that way and what they should do with it, are all answered by God. Part of the solution however, is not merely to throw the baby out with the bathwater, the distinction Jesus made is fine on its own, both as a reminder, that new is not only better, its special, and an instruction, progress slowly, so that you don't mix the two up. Even if you never heard another thing from Jesus and all His teachings, that particular quote would be worth its weight in gold. So being open to being reminded and progressing slowly, do we get somewhere? That ultimately is down to the Holy Spirit. I don't think you can work your way into Heaven, and you can't decide until the next life, what life you think you should be!
This a post-Evolutional attitude, I am adopting here. I'm not saying you can never mutate or you always have to mutate a specific way (I mean if you do, then great, but that's you, that's not everyone), I am saying the pressure you apply to what you think Evolution is is greater if you apply meaning to more than what was. You can't open the door from the inside out. Changing the meaning of mutation, won't help you become a new species, no matter how you try - but transitioning to a position where you understand that speculation is largely relative and consequential will to some extent. Can you make a clean exit, for what you are planning to change into? It's the same for every alternative, at some point you need to deflate what you were - like the caterpillar that wants to be a butterfly -so that you can be what you wanted to be. That's not wrong, just that if you deflate early, your Evolution into something will get mixed up with everything else you have tried to be.
Now you might say "I don't care what I used to be" but that doesn't guarantee that you will survive - you need to survive in some fashion, if you have no Cross to sustain, but at some point you will have to admit there is a Cross that is greater than any specific Evolution. You will live if you trust the Cross, that is what I am saying. I can see that a clean exit is needed, because I know in what way the Cross of Jesus Christ sustains me - if I was to change in to something else, for Christ's sake, what He said about wineskins would be extremely relevant to me (worth laying my life on the line for, even). I hope this has been of some encouragement to you.
God bless.