2021 in Review: Hunter Renfroe brought the power

Welcome to our 2021 Boston Red Sox in Review series. This is, as you can probably guess, where we will be reviewing all of the players who made at least a modest impact on the Red Sox in 2021. Every week day we’ll be deep diving into one player, describing the season in a sentence, looking at the positives from the year as well as negatives, looking back at our one big question from our season preview and looking ahead to the 2022 season. Today we look at Hunter Renfroe’s 2021 campaign.

2021 in one sentence

Hunter Renfroe was one of the best surprises for the 2021 Red Sox, providing stratosphere-cracking home runs and an arm in right field that consistently made aggressive baserunners look foolish.

The Positives

Hunter Renfroe made the most of his first season with the Red Sox, both at the plate and in the field. It’s as simple as that, but let’s break things down a bit more granularly.

On the offensive side of things, Renfroe continued to be the slugger he’s always been. He launched 31 home runs, ranking second on the team behind Rafael Devers’ 38 dingers, and posted an isolated power mark of .242. His power became practically Herculean in August, when he smashed 10 home runs across 89 plate appearances. Renfroe’s massive power numbers were a result of some of the best barrel work in the league, as the Red Sox right fielder ranked in the 88^th percentile in MLB in barrel rate, according to Baseball Savant, although his hard-hit rate was only in the 71^st percentile.

Interestingly enough, Renfroe’s power showed up a bit more on the road than at his new home in Fenway Park, as he hit 14 homers (290 plate appearances) at home and 17 on the road (282 plate appearances). However, Renfroe was a better overall hitter at Fenway, producing a 124 wRC+ at home and a 104 wRC+ on the road. So even if his home run totals weren’t inflated at Fenway, his overall offensive approach certainly played well there.

Speaking of his approach, Renfroe made some improvements at the plate this year, albeit ones that only put him into league average territory. For example, he cut his strikeout rate down to 22.7 percent from 26.6 percent in 2020 and increased his line drive rate from 10.5 percent to 17.6 percent. That second number was still noticeably below average, but his lowered strikeout rate was not only right around league average but the best he’s had in a season in which he’s had more than 40 plate appearances.

Renfroe also took advantage of the pitches he was most comfortable with, absolutely crushing fastballs and sliders for a combined run value of 18. Meanwhile, he continued a recent trend that started in 2020 of going the other way a bit more, although he was still a pull hitter for the most part.

For the counting numbers crowd who want more than just home run totals, Renfroe set several personal records in 2021, including in plate appearances (572), games played (144), runs (89) and RBI (96).

When you added it all together, Renfroe turned in a solid offensive campaign, especially for someone who was league average or worse in three of the last four seasons, according to wRC+. In 2021, Renfroe was 14 percent better than league average offensively based on wRC+, although OPS+ liked him just a bit less (112).

Photo by Billie Weiss/Boston Red Sox/Getty Images

All that offense would have been more than enough to call 2021 a successful season for Renfroe, but he did a lot more than mash. As many baserunners found out, trying to stretch for an extra bag when a ball was hit to Renfroe was a dangerous gambit, as he tied for the MLB lead in outfield assists (16) and ranked 12^th in the league in outfield arm runs above average all while finishing among the top 30 qualified outfielders in defensive runs saved, albeit a mark just below zero.

Taking everything into account, in terms of wins above replacement, Renfroe was a roughly two-win player, with Baseball-Reference giving him a bit more love (2.3 bWAR) than FanGraphs (1.8 fWAR). That may seem a bit low, but we’ll get to some of the reasons why in the next section.

The Negatives

For as great as his arm was, Renfroe wasn’t contending for a Gold Glove. He was a perfectly fine fielder when it came to the other parts of the job beyond throwing, but he was in the bottom half of the league among qualified outfielders in ultimate zone rating, partially due to getting so-so jumps on balls. He also finished in the 17^th percentile in MLB in outs above average.

There were also some clearly identifiable flaws in his offensive game. Renfroe only walked at a 7.7 percent clip, which was his worst mark since 2018 and exactly one percent below league average. The decline was particularly disappointing considering the gains he made in 2019 and 2020 when he posted walk rates of 9.3 percent and 10.1 percent, respectively. In addition, although he cut down his strikeout rate a bit, his chase rate (19^th percentile) wasn’t all that great nor was his whiff rate (39^th percentile). A lot of it came down to his struggles with non-fastball and non-slider offerings, especially curveballs, changeups and sinkers.

Renfroe also disappeared at the most crucial time of the year, as he slashed .194/.326/.250 with a 66 wRC+ in 43 plate appearances in the playoffs.

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The Big Question

Will Hunter Renfroe be more aggressive?

Even though he ended up striking out less frequently in 2021, Renfroe didn’t do so because he wasn’t aggressive. He upped his swing rate to 48.2 percent from 41.6 percent in 2020 and he also went after first pitches at a higher rate than he had since 2017. He paired that with an overall contact rate of around 77 percent, which was easily the best mark of his career if you exclude the 11-game stint that served as his first MLB season with the San Diego Padres.

2022 and Beyond

Renfroe was a steal of a signing by Chaim Bloom last winter, but he’s headed elsewhere for 2022, with the Red Sox sending him to the Milwaukee Brewers in a trade that will bring Jackie Bradley Jr. back to Boston along with a few prospects.