If your build uses Crap4J, then you can track changes to the crap data by activating this plugin.

XML Crap Report filename pattern
This filename pattern is used to find the crap4j report XML file, which will be created alongside your HTML report files.
The pattern is specified in the Ant glob syntax, such as **/target/crap4j/report.xml. The basedir is the project workspace.
Be sure not to include any non-report files into this pattern.