There was a discussion about HOW it works, but not WHY they chose that method: http://stackoverflow.com/questions/11279992/math-behind-google-leap-second-smear-

There was a discussion about HOW it works, but not WHY they chose that method: http://stackoverflow.com/questions/11279992/math-behind-google-leap-second-smear-formula http://stackoverflow.com/questions/11279992/math-behind-goog... My guess is they wanted time to deviate less at the start of the smear window, instead of deviating equally at all points during the window. But perhaps it turned out not to be an issue.