Since some software is constantly changing the solutions for the questions are also changing quite quickly.
E.g. Stanford Parser and NLTK, with different versions of the software, the API to the third-party tool changes. It ends up with legacy answers ranking highest because of the highest votes.
Is there a way to re-rank the deprecated solutions to the bottom?
Downvoting old answers based on score is a workaround for handling something the engine was never designed to handle: the passage of time. When version differences crop up, a weird thing happens: a single question with one or more answers morphs into multiple very similar questions (identical other than the version) posted in a single place. Answers to the different versions cannot be fairly ranked against each other, though that's exactly what sorting by score tries to do.
Problems include:
Sometimes, people have no choice but to use obsolete, deprecated or otherwise questionable technology. One common developer example: "I had to support IE6 until 2015 because my customer said so." Depriving these people of information they need—or, at least, an accurate measurement of the quality of that info—is unhelpful.
Making voting dependent on the score of an existing post confounds the meaning of a vote. The quality of a new answer doesn't change simply because a very high-scoring answer about a now-obsolete feature happened to be present, so its score shouldn't depend on that, either.
Original answerers shouldn't be punished with rep loss just because a feature they wrote about got deprecated years later.
This would have no effect on the problem for those weirdos who sort by age or activity instead of score.
At this point, you might be thinking "well, this is a flaw in the design of the engine". And you'd be right, but it's such a fundamental design element that there's no hope of changing it.
An alternate suggestion: in at least some cases, it might be worth editing posts where time has created ambiguity or problems. Edits could indicate that the information presented was absolutely right at one time, but applies to only version (whatever) of (product), and/or that it is bad to use old versions due to deprecation or security holes or compatibility, etc. And if there's a more modern answer present, it could point that out. Editing was always meant to be a big part of the ecosystem here, after all; a discussion of why people tend not to do it is beyond the scope of this answer.
(I originally wrote this post—and the edit to this post—as comments to PolyGeo's answer, but on second thought I decided it deserved a full answer.)
The best solution for things like this where the question itself is inherently tied to a specific version is to have the question specify a specific version, and therefore limit the answers to only solutions that work for that version.
If a new version comes out that necessitates a change in the solution, a new question should be asked, because solving the same problem is inherently a different question when using a different version of the product (if the difference in versions renders the older solutions obsolete). Users are then able to go to the version of the question for the version of the product they're using, and find the answer ranked on that question according to how effective the community thinks they are for that particular version of the product.
Additionally, for the example you linked, you can just edit your own answer, if you want to include information on each version of the product, rather than posting 5 different answers for all sorts of different situations, and constantly linking between your own different answers.
Yes - the simplest and quickest way to move deprecated (or any less useful) answers downwards is to downvote them, while also upvoting any current and useful answers.
There is no need to downvote old/deprecated answers to oblivion. They just need enough downvotes to get the answers into an appropriate order for today's visitors.
People who know that they are using old/deprecated versions are likely to be in (or get into) the habit of looking past the top few answers for their solution.
