You should start by checking out the "SweetSpotSimilarity" .. it was heavily designed arround the idea of dealing with things like excessively verbose titles, and keyword stuffing in summary text ... so you can configure your expectation for what a "normal" length doc is, and they will be penalized for being longer then that. similarly you can say what a 'resaonable' tf is, and docs that exceed that would't get added boost (which in conjunction with teh lengthNorm penality penalizes docs that stuff keywords)
https://lucene.apache.org/solr/5_0_0/solr-core/org/apache/solr/search/similarities/SweetSpotSimilarityFactory.html https://lucene.apache.org/core/5_0_0/misc/org/apache/lucene/misc/doc-files/ss.computeLengthNorm.svg https://lucene.apache.org/core/5_0_0/misc/org/apache/lucene/misc/doc-files/ss.hyperbolicTf.svg -Hoss http://www.lucidworks.com/
