Cincinnati Reds rookie Sal Stewart enters this week’s series with the Milwaukee Brewers with 20 successful ABS challenges — just two fewer than the entire first-place Brewers’ roster.In the first year of the Automated Ball Strike Challenge System, no player has challenged more pitches than Stewart (30), or won more challenges.The Brewers’ Gary Sanchez has challenged 22 pitches — two more than Stewart has had overturned (20).For those who know Stewart well, like San Diego Padres third baseman Manny Machado, the fact that the 22-year-old is the game’s most prolific helmet tapper isn’t surprising.When asked whether he was surprised by Stewart’s willingness to challenge balls and strikes, Machado, Stewart’s childhood hero-turned-mentor, chuckled before the question was even finished.“No,” Machado said, chuckling again before finishing his thought. “I know his eye — he’s always had it.”Machado cites three reasons Stewart is the poster child for using ABS challenges:

Supreme confidence: Any player who reaches the big leagues must be confident in their abilities. However, even among the ultra-confident, some stand out. The fact that a 15-year-old Stewart walked into a South Florida training facility expecting to hit with Machado and former big-leaguer Yonder Alonso perfectly exemplifies Stewart’s exceptional confidence. If anything, that confidence has only grown since his high school days, when he thought he belonged with big leaguers, to now, when he has proven he belongs with the game’s best.