/*
$data is indeed an array, but it's made up of objects.
Convert its content to array before creating it*/
$data = array();
foreach ($results as $result) {
$result->filed1 = 'some modification';
$result->filed2 = 'some modification2';
$data[] = (array)$result;
#or first convert it and then change its properties using
#an array syntax, it's up to you
}
Excel::create(....