Stats are both critical and useless. Why? Context.
Context matters, just as it does in every day business. You can't optimise and extract the most value from processes on feel, but likewise, lacking context and detail, stats can overlook critical facets which make them either useless or counter-productive. Everything needs consideration. Stats are great to start asking "why". They are also great to highlight numeric performance differences that "gut feel" can't account for.
Bottomline, all of it matters. It just needs to be used effectively and with enough understanding.