[1] Due to his great speed and footwork, as well as a remarkable skill for tackling he was selected to play for the national youth teams throughout every category.
[5] Of the 31 players included in the Los Teros squad for the 2015 Rugby World Cup, only four were playing at a professional level (Mieres, Felipe Berchesi, Agustín Ormaechea and Mario Sagario).
It is for this reason that obtaining the last spot for the 2015 Rugby World Cup was such an exceptional accomplishment since it made Los Teros the only team composed of amateur players out of the 20 taking part in the tournament.
[7] In November 2015, Mieres was tested on a week trial on Coventry Rugby Club, till he finally signed a short contract with the team.
He signed with Canadian club Toronto Arrows ahead of the 2019 Major League Rugby season.