As of 3.0.9 and 3.2.2, all slow operations are logged as part of the COMMAND log component. Prior to this change, slow queries were in the QUERY component, slow writes were in the WRITE log component, and so forth. We should reflect this change on the Log Messages page, as well as consider adding it to the 3.0.9 and 3.2.2 release notes.

SERVER-21776 has more context, but the basic justification is that we want to allow customers to bump the verbosity of a particular log component to 1 on a production system without the volume of log messages being prohibitive.