When searching the "Everything" target in Enterprise, why do eResource Central titles always show up at the top of the list rather than titles from the library catalog?
The reason this happens is that the relevance calculation algorithm considers the digital entries the best match for the entered search terms. Essentially, this is because the digital records' metadata provided by the several vendors are more succinct than the MARC data from the ILS, while MARC records are more expansive and detailed, so the digital records will more closely match most searchers' search terms.
For a detailed explanation of how relevance is calculated by Enterprise's Solr indexing engine, see Search Result Relevance Score Calculation.
For example, if Enterprise is searched for "star wars", the titles in the eRC-based search sources are more likely to be entered as "Star wars" and so are closer to a 100% match, i.e., all terms are in the record and there is less extraneous stuff. Records from the ILS are more likely to be cataloged as "Star wars : a new hope" and the "a new hope" causes it to be less of a match than the digital entries.
Similarly, if the search term is "wicked" to find the book by Gregory Maguire or the soundtrack of the musical, the digital metadata is more likely to be entered as "Wicked" while the MARC data is more likely to be cataloged as "Wicked : the life and times of the wicked witch of the West"; the first is a 100% match where the second is an 16% match (the search term appears twice, i.e., 2x8%).
Product Management has enhancement request DSC-4961 in their tracking system to allow titles from the library's physical collection to be presented first.
The Consulting Services department offers a custom widget that will present each search target's results in a separate tab.