Change "Largest Critical Strike" to "Largest Damage Attack"
and track it for non-crit and ability damage dealt, too. Right now, ADCs and crit bruisers are monopolizing one of the more interesting stats that gets reported at the end of the game.
Champions like 


could all make just as much use of the stat with the high burst they can do if it just kept track of damage numbers in general. It most likely wouldn't change anything for the champions that already use it, since the highest damage attack they do will still probably be a crit to a minion anyway.