I have on occasion been shocked by the rejection of leapfrog articles that I am certain are superior to the original article, but as I look back on the article I suspect I know some of the reasons why these articles were rejected and looking back in several cases I am glad that they were rejected.
The first thing you must do if you want your leapfrog article to be accepted is to ensure that it is at least as grammatically correct as the first article. Because so many articles that are leapfrogged are nearly identical to their previous version the first thing I check when looking at leapfrog articles is grammar. If I find two spelling or major grammar errors more in one article than another I assume that was the reason for the leapfrog and say the more correct version is better.
The second reason I have found for articles being rejected for leapfrog is more problematic and that is length. Having went back and looked at several articles I found myself wandering off the subject. There was little doubt that the article would be better without the ramblings so I cut them out, but the leapfrogs were rejected. Again, because so many leapfrogs are so similar to their other article people rarely read both completely through. Instead they look for the differences and out of context unimportant information can appear to be the better version.
This second way that articles are often rejected also tells you the best way to get an article accepted as a leapfrog. If you find extra information about the subject and add a new paragraph it almost always gets accepted on the general assumption that extra information is superior to less. The truth of this is arguable but by adding an extra paragraph you typically ensure your leapfrog attempt.
Finally is the general improvement of your writing. The most important places that you can make your article better is in the first and last paragraphs. It is often the introduction of your story that makes or breaks the entire rating process. If you can make that hook better you will almost always get a leapfrog improved. The same is true, though to a lesser extent, in your conclusion.
Even if your leapfrog is rejected don't become to despondent. Helium understands that on occasion a person needs to rewrite something and not all leapfrogs get accepted even when they are better. It is for this reason that an article with a failed leapfrog attempt can be resubmitted for leapfrog in a week. So, the final advice is that if your leapfrog is rejected come back in a week and try again.
Leapfrogging is an important part of Helium and you should do more than simply use it to correct grammar. Putting up two of your own articles for leapfrog is an excellent way to test your own style, to learn what appeals to your readers and improve your writing, but in the end you have to have some faith in those who rate as well. Sometimes leapfrogs are rejected because the thing you wrote the first time is simply better.