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How next-level stats boost A.J. Pollock and other free agents

Despite a lengthy injury history, next-level numbers show that signing A.J. Pollock could pay off for the team that adds the center fielder this winter. Mark J. Rebilas-USA TODAY Sports

A general manager chatted last month about the high volume of free-agent relievers and how he thought they would fare in the bidding. If you're one of those pitchers, he said, you better have some advanced metrics that work for you. Because in a time when front offices lay down statistics as the bedrock for whatever they do, there better be underlying numbers that suggest a strong performance is possible and even likely.

A.J. Pollock generated that layer of metrics with the Arizona Diamondbacks last season, despite struggling after he came back from a thumb injury that cost him seven weeks. The center fielder, who turns 31 in a couple of days, had the best rate of hard-hit balls in his career, per Fangraphs. The year-to-year progression in his career:

2012: 32.9%
2013: 37.0%
2014: 30.0%
2015: 34.4%
2016: 27.3%
2017: 35.0%
2018: 44.5%