So, there’s about a hundreth-of-a-percent chance of that happening. About the same as pulling a mythic from a gem key, I think, if I recall correctly that the odds if that are about 1 in 8000 (I might just be thinking of shiny-pokemon occurence rates — my bad, if so).
Unlikely, and sucks for sure, but not so unlikely that there’s necessarily anything wrong.
Now, if he missed 10 times in a row in the same battle, that would be interesting, as that might suggest the seeding is wrong on a per-battle basis or something.
10 times in a row across 10 battles would also be interesting because if we were to say there was only 1 attempt each fight, all of which missed, and only in the 11th battle on the second attempt did one finally work — that would maybe suggest that the first attempt is “doomed to fail” no matter what the percentages say.
But—since one anecdote does not constitute either—all we have is an outlier here (and also I picked 10 out if thin air — I’m not sure what the length of the “streak” would actually have to be to have a confident reason to doubt its fairness/randomness).
Statistics don’t work if one cherry-picks