As noted by Toke in a comment on
While boosting of multi-value fields is handled correctly in Solr 4.0.0, boosting for copyFields are not. A sample document:
The fields name, manu, cat, features, keywords and content gets copied to text and a search for thomasegense matches the text-field with query explanation
If the two last fields keywords and content are removed from the sample document, the score is reduced by a factor 100 (docBoost^2).
(This is a continuation of some of the problems caused by the changes made when the concept of docBoost was eliminated from the underly IndexWRiter code, and overlooked due to the lack of testing of docBoosts at the solr level - SOLR-3885))