Weekly Race

I play quite often and consider myself to be of a reasonable standard.  Last night I led a weekly race with 158 levels, 2nd and 3rd were 60-70 levels behind and 4th had 40 levels.  This morning (10 hours later) we had all dropped 1 place on the leader board and the new leader had 808 levels !!!!!  Seems ludicrous to me that any player could clear a minimum of 760 levels in 10 hours.  Same happened last week - I was miles ahead in the champions race then within a couple of hours I was a hundred or more behind the eventual winner.  Doesn't really matter but could anyone clarify these anomalies for me.