What I really liked in Graylog 3.0 was that I could set the resolution for the message count in the Histogram chart to a specific value (Day or Hour or Minute or …).
See for example my screenshots: In the Hour view I couldn’t see the anomaly, but in the Minute view I can.
I am missing this feature in Graylog versions > 3.0.
It’s possible not so straightforward, by changing widget for Message count - click Edit - click on field timestamp in ROWS section, uncheck automatic, and select interval (Seconds, Minutes, Hours, Days, Weeks, Months).