A little JS snippet you can run from the browser console of the Slack stats page to see the "true ranking" of top message senders

slack-messaging-rank.js

// 1. go to https://{YOUR_SLACK_DOMAIN}.slack.com/stats#members
// 2. open the browser console
// 3. enter this (note: it might warn you that pasting code is bad):
$.post(`/api/team.stats.listUsers?_x_id=${boot_data.version_uid.slice(0,8)}-${Math.round(performance.now()*100)/100}`, {
  count: 50,
  sort_prefix: 'chats_sent',
  sort_dir: 'desc',
  date_range: '30d',
  set_active: true,
  token: boot_data.api_token,
  _x_mode: 'online'
}).done(({stats}) => console.table(
  stats.map(({
    first_name,
    last_name,
    username,
    messages_sent,
    chats_sent,
    days_active
  }) => ({
    name: `${first_name ? `${first_name} ${last_name}`.trim() : username}`,
    /*messages_sent,*/
    chats_sent,
    days_active,
    da_chat_rate: Math.round(chats_sent * 10 / days_active) / 10
  })).sort((a, b) => b.da_chat_rate - a.da_chat_rate)))