I don't know anything about lyric sites. Per Glenn they do something with regard to compensating publishers. I don't how much or substantive it is. You'd have to look at the above article and the earlier article that is referenced by the SELand one to see the specifics.
Clearly the knowledge box grabs traffic from visitors and likewise starves websites. I'm sure the impact varies. Glenn referenced the difference between search phrases for "song lyrics" and song lyrics meaning". He has access to data we don't but evidently both phrases are fairly voluminous.
Across the board the knowledge box takes traffic from websites. If the sites are monetized with adsense google is pulling the traffic into its own world of google pages and hoping for clicks on ads wherein it doesn't have to share the income with website owners. (that is a helluva partner, isn't it?)
I usually look at these things from the perspective of small businesses and local sites. The biggest hit on local sites was the recent conversion from a carousel view of up to 20 choices of local competitors to a miserly view of 3 businesses in what I like to call the "NO KNOWLEDGE PAC"
It hit restaurants and hotels within the US and accessed via the US via google.com .
the NO KNOWLEDGE PAC offers 3 miserly choices of local restaurants or hotels (and some other businesses) with NO MAP, NO PHONE NUMBER, NO ADDRESS, and NO LINK. Essentially all the information a consumer wants. One writer likens it to Alice in Wonderland
If one clicks on a restaurant in the NO KNOWLEDGE PAC there is a lot of information in a subsequent Knowledge Box on that restaurant that takes up all the screen real estate. Its sort of stunning but when reviewing the info on a restaurant a link to the restaurant menu usually goes to another website, not the restaurant site: Not in all cases, but often enough.
For instance if you clicked on this restaurant via a search for "Italian restaurants Shaw" (Shaw=a neighborhood in Washington DC). and then clicked on the picture in the NO KNOWLEDGE PAC you get a very large knowledge box about the restaurant, including a link to the restaurant menu that is not from the website, but from UrbanSpoon.
That isn't good knowledge. That is a secondary source. The restaurant website has far far better menu detail.
I'm sorry. I look at the knowledge box and see Google intent on starving website traffic. Its a significant issue imho.
In the case Glenn described above, Lyric sites lost something in a range of 17% to over 40% of their traffic for certain search phrases; (larger losses per WMT data). Those are killer losses.