Jace Peterson has emerged as a surprise contributor for the 2021 Milwaukee Brewers

A successful baseball team needs depth. The 162-game season is a long and winding road filled with ups and downs, and an entire roster cannot remain completely healthy for the whole year. This creates opportunities for those who were not otherwise counted to be contributors to become potential role players. Having quality depth can be the difference between a club being sunk by injuries or staying afloat when their roster is at less than 100%.

For the 2021 Brewers, that depth has come from a rather unlikely source in Jace Peterson. There was no reason to expect any level of productivity from Peterson. The 31-year-old entered this season with a career slash line of .227/.317/.331 (77 wRC+) and a -0.5 fWAR. Milwaukee even booted him off their 40-man roster in late May. However, he quickly found himself back with the team when Kolten Wong’s left oblique troubles resurfaced.

Fast forward a few months to September. Among Brewer hitters to amass at least 200 plate appearances this season, Peterson’s 128 wRC+ trails only Willy Adames. The utility man has been an on-base machine, reaching at a pristine .402 clip.

In addition to filling in at the keystone during Wong’s absence, injuries to Eduardo Escobar and Tyrone Taylor have opened up playing time for Peterson at third base and in the outfield. He’s been more than just a passable fill-in for these players. His offensive output has been a legitimate boost for a contending Brewers team. The veteran’s impact has been felt throughout the team’s current series against the San Francisco Giants. On Monday night, he reached base four times in a key victory. Two nights later, he drove in the winning run with a clutch opposite-field single.

While his contributions have certainly been welcome, one cannot help but wonder how on earth he has been this productive. Peterson has always possessed the ability to work a walk, but he never came especially close to being a useful hitter at the big-league level.

How is the versatile defender pulling it off? A peek at his batted ball luck reveals that he is benefiting plenty from the cards falling in his favor. Not only is his .346 BABIP well above the league average, but he has never approached it before in his career. It looks like an obvious outlier.

A good amount of his breakout can be attributed to exceptional luck, but it’s not exclusively smoke and mirrors. To Peterson’s credit, he has improved his batted ball profile. In addition to boasting career-highs in hard hit rate and barrel rate, he is elevating the ball more. Peterson’s 12-degree average launch angle is a personal best, as is his 36% fly ball rate.

According to Statcast, Peterson carries an expected slash line of .242/.379/.386. This confirms that a good amount of over-performance is occurring, but such a line would still make him a slightly above-average hitter. Similarly, Baseball Prospectus pegs him for a deserved line of .247/.367/.389 and a 106 DRC+. While Peterson may not be nearly as potent at the plate as his surface-level stats indicate, the deeper metrics hint that he has quite possibly fashioned himself into a useful bat.

Sustainable or not, Peterson’s output has been a dramatic improvement from the many seasons that featured Hernan Perez and his notoriously low on-base percentages manning the utility role. Unlike most bench players, there has been little to no difference offensively between Peterson and any regular player he may be filling in for. A winning team needs strong depth, and Jace Peterson has supplied exactly that.

Statistics courtesy of FanGraphs, Baseball Savant, and Baseball Prospectus.