The St. Louis Cardinals powered through the Atlanta Braves on Wednesday night after scoring 10 runs in the first inning, the third time a team had ever scored that many runs in a playoff game’s opening frame. However, that type of offensive outburst hasn’t been the Cardinals’ norm, and won’t likely be their biggest asset heading into a meeting with the Washington Nationals in the NLCS.

The Cardinals scored double-digit runs in an inning just once this season, a 10-run performance in the sixth inning against the Cincinnati Reds in July, and they averaged less than five runs per nine innings in 2019. Of the 10 teams that qualified for the playoffs this year, the Cardinals scored the fewest runs (764). They were also the only playoff club to rank in the bottom half of the majors in on-base plus slugging, with a .737 OPS.

Instead, St. Louis wins the old fashioned way: with solid defense.

In fact, they are the first team in baseball history to go from committing the most errors in one season (133 in 2018) to the fewest in the next (66). Second baseman Kolten Wong, a solid defender, took his game to another level and led second basemen with 14 defensive runs saved and a league-leading 78 percent revised zone rating, a metric that measures the proportion of balls hit into a fielder’s zone that he successfully converted into an out.

Outfielder Harrison Bader was credited with 13 defensive runs saved, third-most among center fielders, and saved 4.3 more runs than an average outfielder by preventing runners from advancing on the base paths. Bader’s 21.8 ultimate zone rating per 150 innings also led all qualified outfielders in 2019. And Paul DeJong finished fourth among all shortstops for defensive runs saved (14), third in UZR per 150 (9.6) and second in revised zone rating (80 percent). Those three homegrown defensive stars were complimented by Paul Goldschmidt, a three-time Gold Glove first baseman acquired last offseason from the Arizona Diamondbacks, and Marcell Ozuna, a Gold Glove-winning outfielder acquired from the Miami Marlins the previous offseason. Goldschmidt ranked fourth among first basemen for UZR per 150 (2.5) and Ozuna ranked 10th among outfielders in the same metric (8.6 UZR per 150).

Loaded with defensive talent, Louis turned 168 double plays in 2019, the second most in the majors, and no team in baseball was better at converting grounders into outs, per Stacast data. Based on the launch angle and exit velocity of each groundball put in play, we could have expected the Cardinals’ opponents to produce a .242 batting average in 2019. Instead they batted just .215. (MLB teams combined to hit .239 on ground balls this season.)

What’s remarkable is that St. Louis doesn’t rely on the shift to augment these results. Manager Mike Shildt only called for a shift 16 percent of the time in 2019, the sixth-lowest rate in the game, and almost all of those shifts (819 out of 939) came against left-handed hitters.

Washington isn’t a groundball-hitting team, per se — fewer than 42 percent of the Nats’ batted balls in play this year were on the ground, a below-average rate — but the Nationals did experience above-average results on those at-bats. The team hit .248 on ground balls, tied with the Milwaukee Brewers for the highest average in the NL. However, St. Louis pitchers are particularly good at inducing ground balls. Batters hit a grounder against the Cardinals 45 percent of the time (fourth highest in the majors in 2019) and one of their starters, Dakota Hudson, led the majors with a 57 percent groundball rate. Hudson faced the Nationals twice this year and held the Nationals to 2 for 21 batting on ground balls, which accounted for 22 of the 39 balls put in play.

Two other St. Louis pitchers who will get the ball early in the NLCS were excellent at keeping the ball on the ground. Likely Game 2 starter Adam Wainwright’s groundball rate (49 percent) ranked 14th in the majors in 2019. Game 1 starter Miles Mikolas’s rate (47 percent) ranked 20th, giving St. Louis two more pitchers who take advantage of the defense behind them. In seven games against the Nationals this season, St. Louis pitchers as a group held the Nats to a .196 average on ground balls, which made up almost half of all balls put in play by Washington (93 of 187) in these contests.

Strong defense might seem like a baseball relic, but it also might be the Cardinals’ best weapon against the Nationals.

Read more: