Log data provides the most granular view into what is happening across your systems, applications, and end users. Logs can show you where the issues are in real-time, and provide a historical trending view over time. Logs give you the whole picture.
A June 2014 Gartner Report on Security Information and Event Management (SIEM) reveals that many surveyed SIEM users indicate «cost» (both in terms of price and effort) as being one of the biggest challenges presented by traditional SIEM tools of today. The irony of this insight is that reducing the cost and complexity of managing security information and events should be the primary function of a SIEM tool.