using this
in an parameter statement,does not change its context. it still refers to the same object as it were anywhere else in the surrounding scope
function x(){
//this in here and the function parameter call refers to the same object
console.log(this)
$(".tournament-thumb").backstretch($(this).data("url"));
}
in jQuery, if you pass a callback to a function, inside those functions this
will most probably refer to the dom element currently being used.
If it were something like
$(".tournament-thumb").backstretch(function(){
//do something
//here this might refer to the tournament-thumb element
});