I believe if you check someone profile stats, it showed his Raw stats. Let say for example you seeing him as 1M A/D stats. But when he check his own stats all the boosted bonus added to his stats such as, 20% infantry attack, 20% magic, machine, beast attack, plus the 3% alliance attack in his dozens of units that comes with it, plus other units with attack bonus, & also your attack skills helps too. These things will add up in his Attack stats & he's seeing more than his 1M Attack stats.
My Guild teammates seeing my stats 1,900k Raw attack & is 600k less than my boosted attack. That's why i don't like asking them my Raw attack anymore cause it is too low than my boosted attack
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I hope this info helps...