As the St. Louis Cardinals surge through May, they’re doing so by playing some of their best baseball in recent memory.

The Cardinals (24-20) are a season-best four games over .500. They have won 14 of their last 19 games and currently sit one game out of first place in the division. Players across the board are taking major steps forward. Brendan Donovan’s .313 batting average is the sixth-highest in the National League. Victor Scott II’s six Outs Above Average (OAA) is tied for the third-best in baseball, and his 13 stolen bases are the third-most in the league. Masyn Winn continues to show why the Cardinals believe he’ll be their long-term shortstop, and Kyle Leahy continues to be one of the most underrated set-up men in the game.

The majority of the industry dismissed the Cardinals before the season began, citing the organization’s lack of offseason activity and a transition plan that didn’t provide much direction for the immediate future. But St. Louis has forced its way into early-season relevancy, especially after its convincing series win at Philadelphia this week.

“They can beat you in a lot of different ways,” Phillies manager Rob Thomson said after the series. “They can run, they can steal bases, they can play some small ball when they need to. They’re a great ball club.”

What has largely stood out for St. Louis this season has been its consistently stellar defense. The Cardinals have registered an MLB-high 24 OAA — six more than the next highest team (the Houston Astros at 18). They’ve also prevented the most runs (19) and are in a four-way tie with the Astros, Phillies and Kansas City Royals for best team fielding percentage at .990.

But one thing the defense has done that can’t be measured in the box score? It has aided the starting rotation, which many projected as the team’s weakest link heading into the season. Instead, it’s become a strength. Cardinals starting pitchers have combined for a 3.85 ERA over 390 2/3 innings, with opposing hitters averaging just .238. They largely remain a pitch-to-contact staff, despite most organizations trending away from that strategy, instead focusing on high velocity and enticing hitters to chase. They’ve found success by utilizing weak contact and letting their defense go to work: St. Louis’ starters lead baseball in ground-ball outs (425), and its 34 home runs allowed trail only the New York Mets (28).

The rotation has done a considerable job keeping the Cardinals in ball games, but it’s no coincidence. Dating back to spring training, pitching coach Dusty Blake and manager Oli Marmol were deliberate about how the first six weeks of the season would play out, mapping out team off days and workload to ensure the rotation could maximize its effort while remaining well-rested. It’s why St. Louis used a hybrid six-man rotation in mid-April and why the coaching staff committed to keeping each starter on a six-day schedule instead of the traditional five. With limited pitching depth in Triple A, keeping the starters healthy and effective became a top priority.

“It was a matter of keeping everybody on a six-day schedule, with health and getting through April being the No. 1 filter for it,” Marmol said. “We accomplished that, and everybody’s healthy, which is a task in itself. I’m glad we did what we did, because all of our starters feel really good right now and are having success.”

Mission accomplished, at least for the time being. But is it sustainable?

Let’s break this down by expected ERA (xERA) and expected slugging percentage (xSLG). For this exercise, we’ll exclude Steven Matz, who will be used in relief for the rest of the month (but could return as a spot starter in June when the Cardinals have just two scheduled off days).

The underlying metrics point toward Sonny Gray and Matthew Liberatore sustaining their trajectories (though the Cardinals would like to see Gray’s ERA drop). This matches up, as they are the two pitchers on staff who also generate the most swings and misses. But for Erick Fedde, Miles Mikolas and Andre Pallante — all of whom are considered ground-ball pitchers — it’s not nearly as convincing.

That’s why Blake has heavily emphasized the chase pitch. The simplified approach: Attack the zone quickly to establish a favorable count (0-2 or 1-2, preferably), then try to induce a chase pitch outside of the zone. It’s not easy, especially when pitchers are finding success utilizing their strengths, but establishing additional weapons will be pivotal for this staff.

“Every year, the league adapts to what you do,” Blake said. “We have to be aware enough to see how April went, what was new, what’s different, why is this working better, why is this not getting the same amount of effectiveness? By having some level of awareness and intentionality of how we’re using that information, that will help us progress.

“We’re going to be direct and do the things we’re good at, but the ancillary pitches, locations, strategies that help complement that so we don’t overexpose ourselves is a big part of this as the season goes.”

The Cardinals are not fully shifting away from what has been working for them this year, but they are trying to diversify their overall approach. For players like Mikolas, who has made his career out of being a pitch-to-contact arm, it continues to be a work in progress.

“I think you look at our rotation, we have a good amount of guys on the other side of 30, guys that came up and were drafted in an era where it was three pitches or less (per at-bat), get some ground balls, pitch to contact,” Mikolas said. “It’s different than how you’re seeing guys develop these days, where there’s a lot more emphasis on swing and miss.”

But that doesn’t mean he’s opposed to it. Mikolas has reworked his sequencing to try to induce more chase. It hasn’t been reflected in his strikeout numbers — he’s struck out just 13 batters over his last five starts — but he is seeing better overall results as the chase rate leads to even weaker contact.

“Getting better with some of my sequencing and being able to go after strikeouts is something that’s going to help me earn that trust back,” Mikolas said. “That’s a benefit of going outside the zone — not just the swing-and-miss — but quality of contact is much softer, right? It’s not your 100 mph groundball to the shortstop. A lot more good things can happen when you’re out of the zone at the right time, and the quality of contact is a lot less.”

In Pallante’s case, he’ll need to be less reliant on the groundball as he advances through his career.

“It’s always been something I’ve worked on, mainly because so much of the work I do is about throwing strikes and throwing pitches in the zone,” Pallante said. “There are very few guys in this game who consistently get swing-and-miss in the zone.”

Because he has been so effective in the zone, the Cardinals don’t want to deter Pallante from throwing there. They do want him to tweak how often he goes there. It’s the same approach Blake is preaching across the board to his starters.

“Swing-and-miss is batter-reliant, right?” Pallante said. “The batter has to swing in order to get swing-and-miss. So a big emphasis as a team that our pitching analysts and pitching coach push is going to areas that get swing-and-miss, which is usually off the plate or under the zone. To be able to be in those positions, you have to be ahead in the count. So we emphasize getting ahead of the count so we can throw to our chase location so we get our swing-and-miss.”

As the Cardinals look to continue rolling, they know they can only go as far as their rotation will take them. Preserving pitcher health will continue to take precedence. Beyond that, the concentrated effort to induce swing-and-miss, while not entirely shifting away from the strategies that have worked so far, continues to be just as important.