Cardinals fans have good reason to be excited by the Mariners' dominant pitching

While the Toronto Blue Jays ended up representing the American League in the World Series this year, the baseball world got a first-hand look at the incredible pitching staff the Seattle Mariners have built which put them on the brink of their first-ever World Series appearance during their postseason run.

St. Louis Cardinals fans should hold out hope that their organization may be able to emulate that success in the coming years.

That rotation that is headlined by Bryan Woo, Logan Gilbert, George Kirby, Bryce Miller, and Luis Castillo, and bullpen that features the likes of Andres Munoz, Matt Brash, Eduard Bazardo, Gabe Speier, and other dynamic arms, was built from a mix of excellent drafting and development, trades, free agent signings, and sneaky waiver wire pick ups that has made Seattle the darling of pitching in Major League Baseball. And because of that, the Cardinals decided to snipe one of their pitching development gurus to help oversee their pitching during this rebuild.

The Cardinals brought in Matt Pierpont from the Seattle Mariners to lead their pitching development

Last offseason, the Cardinals' new president of baseball operations, Chaim Bloom, and his assistant general manager of player development and performance, Rob Cerfolio, went out and hired Matt Pierpont to become the club's director of pitching. Prior to being hired by St. Louis, Pierpont spent almost four years with the Mariners organization in different roles, ranging from pitching coach to pitching coordinator.

At the time, Pierpont was a finalist for multiple big league pitching jobs across the industry, but ultimately landed with the Cardinals to become their director of pitching. It's been well documented at this point how poor a job the Cardinals have done since the mid-2010s in developing their own pitching, something that Pierpont experienced firsthand the fruit of what happens when an organization nails that.

“What I saw done really well in Seattle and what I learned there is, when you create homegrown starting pitchers that have a ton of value, that saves the team a lot of money in terms of spending on your roster,” Pierpont told Katie Woo of The Athletic back in spring training. “Now that can be allocated somewhere else. Starting pitchers from within your system can add a crazy amount of value to the organization, so that will always be the top priority.”

Here are some tangible examples of how that had played out in Seattle in 2025. Four of the Mariners' five starters this year had three or fewer years of service time, with two in arbitration and two pre-arb. When it came to the Mariners' top bullpen arms, not a single player was acquired on a major league free-agent contract. The cost benefits of building a high-level pitching staff this way are hard to overstate. Just look at this chart of how much value the Mariners' pitching development brought them in 2025:

The Mariners spent $42.7m combined on their rotation and four of their top bullpen arms and received $128.7m in value from them, amounting to a whopping $86m in surplus value over the course of the year. It will be extremely difficult for them to repeat that feat in future years as their arms become more expensive and injuries occur, but that's not the point. What Seattle has built over the last few years is a pitching staff that consistently produces more than the financial investment they pour into it, thus giving them one of the best staffs in the game and the ability to add to their position player core or bring in even more pitching as needed.

It's not like 2025 is the only year they've reaped these rewards. Gilbert, Kirby, Woo, and Miller have become staples of their rotation over the last few years and have been outproducing their financial commitment by a mile. In total, the Mariners have paid those four pitchers about $24.2m in big league salaries since 2021, and each of them combined has produced $319.1m in value for the Mariners, and an incredible $294.9m in surplus value over that stretch.

The Cardinals actually used to be a lot like the Mariners. In the early to mid-2010s, they would have a few veteran starters on bigger contracts like Adam Wainwright, John Lackey, or Jake Westbrook, but their pitching staff was littered with young arms like Michael Wacha, Shelby Miller, Carlos Martinez, Jamie Garcia, Lance Lynn, Trevor Rosenthal, Kevin Siegrist, and so many more who gave the Cardinals a massive advantage over their opponents.

Recently, the Cardinals have had to rely heavily on the production of veterans they acquire in free agency or through trades because of how their pitching pipeline has dried up. 2023 was the disaster example of this, but even in 2025, when some arms have started to sprout up, they still are miles beyond the Mariners in what Pierpont was able to help shape over there. Here's a chart of the money the Cardinals spent on their rotation and bullpen in 2025 and the value it produced for them:

If we expanded this list further to include names like Matt Svanson, Kyle Leahy, and Riley O'Brien, the Cardinals would end up in the positive in surplus value, but again, that's not the point. The point is that the Cardinals spent $77m on their top arms in 2025, and it resulted in a mediocre pitching staff. The Mariners invested $42.7 million in their top arms, and it helped bring them to within a few outs away from a World Series appearance.

Under Pierpont, the Cardinals made plans to implement Hawk-Eye systems in their affiliate ballparks, a computer vision system used to track ball trajectory and profile, as well as implement biomechanics with ball flight metrics, something Pierpont saw the Mariners and other top teams leveraging to improve their own pitching development.

Along with that, we saw the Cardinals make shifts in the kinds of arms they targeted in the 2025 MLB Draft, selecting flamethrower Liam Doyle with the fifth overall pick, and grabbing other high velocity or toolsy arms like Tanner Franklin, Cade Crossland, Ethan Young, and more.

During the postseason this year, a lot of conversation was had about the high volume of sliders that Mariners pitchers threw to opposing hitters, something that announcers continued to be baffled by. Well, it's something Seattle has been preparing their pitchers for years down in the minors, allowing their big league arms to adjust their game plan in order to have an advantage over certain opponents. It is this level of attention to detail and pushing the boundaries of what the sport knows, two characteristics Chaim Bloom continues to preach, that allows an organization to get the competitive advantage that the Mariners have developed.

The Cardinals' rebuild is going to be marked by a lot of things, but arguably the most important aspect of it will be their ability to get back to producing pitching at a high level. Over the last two years, the Cardinals have shown the ability to get the most out of bullpen arms that they acquire from other organizations or develop themselves, and they now have a growing group of young arms in the minor leagues with a lot of intrigue. If Pierpont can continue to bring some of that Seattle magic to St. Louis while innovating and finding the cutting edge of what makes for great pitching in today's game, the Cardinals will be able to flip the narrative on their pitching pipeline over the next few seasons.