There still are some key Red Sox position battles to sort out over the next week, including competitions for second base and the final two spots in the starting rotation.But backup catcher? That one apparently is over, and the winner is a former New York Yankees prospect.Boston on Thursday optioned catcher Blake Sabol to minor league camp. Sabol was competing for the backup catcher job with Carlos Narvaez, who now is in line to open the season as the second option behind Connor Wong.The news arrived two days after MassLive reported Narvaez was "the leader" for the backup catcher job.The Red Sox acquired Narvaez in an offseason trade that sent pitching prospect Elmer Rodriguez-Cruz and international bonus pool money to the Yankees. Boston needed catching depth after sending top prospect Kyle Teel to the Chicago White Sox as part of the trade for ace lefty Garrett Crochet.Narvaez is a glove-first catcher with solid offensive upside. Last year, he slashed .254/.370.412 with 11 home runs, 20 doubles, 56 walks and 105 strikeouts in 96 games for New York's Triple-A affiliate.As for Boston's infield dilemma, all signs point toward Kristian Campbell playing second, Alex Bregman playing third and a disgruntled Rafael Devers moving to designated hitter.More MLB: Red Sox Rumors: Huge Rafael Devers Update Amid Mounting Trade Speculation