A draft is something you should keep to yourself. It is an unfinished book. You wouldn't serve someone a half-cooked meal, would you? Especially not if you were running a restaurant and expected them to pay for it? So don't send a publisher a draft of your book. It's not their job to tell you what to do with it to finish it, and it's certainly not their job to finish it for you; it's your job to know what it needs and do it.
There are two principal reasons for a publisher to refuse a book: it's crap and always will be; it's still crap but you could have made it OK. Oh, and there's a third - you sent them a book that is not the type they publish, or that they already have with a slightly different title. There's nothing you can do about the last bit except look at their catalogue and make sure they haven't just printed a book that is pretty much the same. The others are all in your control. (Most of this is covered wonderfully by the Crabbit Bat Nicola Morgan on Help! I Need a Publisher - write the right book at the right time in the right way and send it to the right publisher.)
There's sort of a fourth, which is that you have sent a good book to someone who just doesn't like it. That's bad luck and there is nothing you can do about editors' (or readers') tastes.
The issue of the draft addresses reason number two: it's still crap but you could have made it OK.
Now, all this doesn't mean that your book won't need any editing. Every book benefits from editing - and copy editing and proof-reading. But it should be finished in your view. The editor will still improve it. And if they can't improve it, they will be paid for doing nothing, so they can be grateful to you. If you can still find things - any things - wrong with your book it is not ready to send in.
Caveat: no book is ever perfect. This is not a licence to hold onto your book forever because it doesn't match up to the Platonic ideal you conceived when you planned the book. It has to be publishably good, not worthy of having been written by an omniscient god. If you hold on to your book for ages, tweaking and pithering about with it, you will never submit anything. And if you have a deadline imposed by a publisher, you have to submit by that deadline. Don't hang on to it for a bit longer because it isn't quite right. Read this post for a rant about the importance of meeting deadlines. Is this incompatible with everything else I have said? Not really - you just need to start the book early enough, and write it quickly enough, to leave time to correct and improve it before the deadline. That's easy, isn't it?