Why are Yahoo and Bing search results so bad?

I've been working on a few new websites that I've created, and SEO is definitely a strange and interesting art.  But one thing I've noticed is that Google seems to be doing a much better job at ranking pages from the website I'm working on for relevant searches than Bing or Yahoo.

Ok, now I know you're saying, "Well, you're biased - of course you expect your site to be ranked high."  All right then, here's a little challenge.

I made a word search puzzle creator at Knowledge Mouse.  Someone created a word search puzzle about geology, and the title is "Layers of the Earth and Tectonic Plates".  For the HTML title of the page - it's "Knowledge Mouse - Layers of the Earth and Tectonic Plates Word Search Puzzle".

Now, let's consider a web search for "Layers of the earth and tectonic plates word search".  I would argue that my site is probably the #1 most relevant result for that search.  Possibly there are a couple of other pages you might feel are pretty relevant, but I bet most would agree that my page belongs in the top 5 - I mean, how many other word search puzzles about earth layers and tectonic plates are there on the web?  And indeed it shows up as #1 on Google.  Great!

Now, let's try Bing and Yahoo.

For Bing, the first result is a usgs page that actually is a word search about plate tectonics.  Not bad; I still think the Knowledge Mouse page is probably more relevant, but the usgs page at least seems to be somewhat relevant.  Now that page seems to require a Java app to show the puzzle, plus the page seems to have problems rendering in IE9, but we'll ignore all that.

The rest of the first page of results on Bing has one other relevant site, a word search puzzle on Layers of the Earth from wordsearchfun, but the rest seem pretty irrelvant, including a dictionary.reference.com page defining "tectonic plate" and a Wikipedia article.

How about Yahoo?  The first result is that same usgs page.  And wordsearchfun also appears.  As well as the dictionary.reference.com definition of "tectonic plate" again.  And again the rest of the results are pretty much irrelevant (including another Wikipedia article).

And for both Bing and Yahoo, I clicked on the next page of search results, and the next, through at least 20 pages, and nowhere was the Knowledge Mouse puzzle to be found.  Suffice it say that most of the 20 pages contained irrelevant results.

Maybe the page is too new and hasn't been indexed yet?

Nope, if you add "puzzle" to the end of the search query, then all of a sudden Knowledge Mouse pops up to the top on both Bing and Yahoo.  Hmm, are these guys sharing algorithms?

So why are Google's search results so much better than Bing and Yahoo?  I don't know, but if you're reading this, I bet you didn't arrive at this page through a search on Bing or Yahoo!