Buster Olney's top wild-card matchups

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Every fall, the postseason surprises us with new heroes. Like Joe Kelly, who was nearly left off Boston's playoff roster in 2018 because of ineffectiveness but suddenly emerged as a shutdown reliever on the Red Sox's drive to a championship. Or the 35-year-old Howie Kendrick, who, at the end of an excellent career, had moved into a part-time role for the 2019 Nationals before delivering the biggest hits in the biggest moments. Or how about Christian Colon, whose one plate appearance in the 2015 World Series resulted in a tiebreaking pinch-hit in extra innings.

It's impossible to predict -- but for every team in every postseason series, there are discernible fault lines that could break or make a deep run.

The top dozen matchups of the wild-card round of the playoffs: