The Seattle Mariners are still putting the finishing touches on their roster, continuing a series of smaller but meaningful moves as they try to sort out the fringes of the team.
One of those moves came Tuesday, when a seemingly simple trade created a ripple effect that could cost the organization a former first-round draft pick.
Seattle completed a deal with the Minnesota Twins to acquire catcher Jhonny Pereda, a depth addition aimed at strengthening the organization’s catching situation. Pereda gives the Mariners another option behind the plate, particularly valuable given how physically demanding the position is and how often teams need reliable depth over the course of a long season.
However, bringing Pereda into the organization came with an immediate consequence. In order to create room for him on the 40-man roster, the Mariners were forced to make a tough decision, ultimately designating right-handed pitcher Jackson Kowar for assignment.
Kowar’s designation for assignment means he has been removed from the 40-man roster and placed on waivers. During this waiver period, other Major League teams will have the opportunity to claim him. If another club puts in a claim, Kowar would leave the Mariners organization entirely and join his new team. If no one claims him, Seattle would be able to outright him to the minor leagues, allowing them to keep him within the system.
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The move is notable largely because of Kowar’s pedigree. He was once considered a significant piece of Seattle’s future, having been selected in the first round of the MLB Draft. At the time, he was viewed as a polished college arm with the potential to move quickly through the minor leagues and eventually contribute at the big-league level.
Things, however, have not unfolded as smoothly as originally hoped. Injuries, inconsistency, and struggles to establish himself have slowed Kowar’s progress and limited his impact at the Major League level. While he has shown flashes of promise, those moments have not been consistent enough for the Mariners to justify keeping him on the crowded 40-man roster, especially as the team looks to maximize flexibility heading into the season.
For Seattle, this decision reflects the ongoing challenge of roster management. With a competitive core in place, the Mariners are constantly balancing upside against immediate needs. Depth pieces, even those with intriguing backgrounds, can become expendable when roster spots are at a premium.
From the organization’s perspective, adding Pereda addresses a more pressing need. Catching depth is critical, and teams often prioritize reliable options at that position, particularly ones who can handle pitching staffs and provide coverage across multiple levels of the system. In contrast, Kowar had fallen into a category where his potential upside no longer outweighed the roster constraints facing the club.
Still, the situation is far from resolved. Waiver claims can be unpredictable, and another team may see Kowar as a worthwhile reclamation project, especially given his draft status and remaining upside. If that happens, Seattle would lose him for nothing more than the roster spot he occupied.
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If Kowar clears waivers, the Mariners may retain him as organizational depth, giving him another chance to regroup and possibly work his way back into consideration down the line.
Ultimately, this sequence of moves highlights how even minor transactions can carry significant consequences. For the Mariners, it’s another example of the difficult decisions required to fine-tune a roster, where adding one player often means risking the loss of another.
At one point, Jackson Kowar carried the type of résumé that suggested a long and successful major league career was ahead of him. Coming out of the University of Florida, one of the premier collegiate baseball programs in the country, Kowar was viewed as a polished, high-upside arm.
That belief was reinforced in the 2018 MLB Draft, when the Kansas City Royals selected him in the first round. Being taken that high placed significant expectations on his shoulders and positioned him as a key piece of the organization’s future pitching plans.
Kowar moved through the Royals’ system with the reputation of a pitcher who possessed both quality stuff and strong fundamentals. His collegiate background suggested he would be able to adjust quickly to professional baseball, and for a time, the organization believed he could develop into a reliable rotation option or at least a valuable contributor at the major league level. However, once he reached the highest level of the sport, the results did not align with the early projections.
Over the course of his career, Kowar has appeared in 54 major league games. Most of that time came with Kansas City, where he spent parts of three seasons trying to establish himself. Later, he found additional opportunities with the Seattle Mariners, appearing for them during the 2025 season. Despite the change of scenery, consistent success at the major league level has remained elusive.
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Statistically, Kowar’s MLB numbers highlight the struggles he has faced. Across 91.0 innings pitched, he has posted a career earned run average of 8.21, a figure that reflects ongoing difficulties with run prevention.
During that span, opposing hitters have tagged him for 83 earned runs, frequently capitalizing on mistakes and forcing him into high-stress situations. Command has also been an issue, as evidenced by the 58 walks he has issued, often putting extra runners on base and compounding his challenges.
That said, there have been flashes of the ability that once made Kowar such a highly regarded prospect. He has recorded 90 strikeouts in his major league career, showing that his raw stuff can still miss bats at the highest level. Those strikeout totals suggest there is underlying potential, even if it has not yet translated into consistent performance or dependable results.
Kowar’s professional journey serves as a reminder of how difficult the transition to Major League Baseball can be, even for pitchers with elite pedigrees. A first-round draft status and strong amateur background do not guarantee success, and many talented arms struggle to find stability once facing the game’s best hitters on a nightly basis.
While his career ERA and overall numbers are discouraging, his experience, strikeout ability, and pedigree continue to make him an intriguing case as he works to redefine his role and carve out a more reliable path at the big-league level.
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Jackson Kowar entered professional baseball carrying the kind of résumé that usually signals long-term success. Coming out of the University of Florida, one of the premier programs in college baseball, he was widely viewed as a polished and dependable arm.
That reputation led the Kansas City Royals to select him in the first round of the 2018 MLB Draft, a decision that reflected both his collegiate dominance and the belief that he could become a meaningful piece of a major league pitching staff. At the time, Kowar was considered a safe bet — a pitcher with command, composure, and the tools needed to handle advanced competition.
Since then, his major league journey has been uneven. Kowar has appeared in 54 MLB games across his career, logging time over parts of three seasons with Kansas City before spending time with the Seattle Mariners in 2025. While simply reaching the majors is an accomplishment in itself, his performance at that level has not matched the expectations that followed him out of college and into pro ball.
Statistically, his results have been difficult to ignore. Over 91 innings pitched in the majors, Kowar owns a career ERA of 8.21, a number that illustrates just how challenging his outings have often been.
During that span, he has surrendered 83 earned runs, frequently struggling to limit damage once runners reached base. Command issues have played a role as well, as evidenced by the 58 walks he has issued, often putting himself in trouble before hitters even put the ball in play.
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There have been some positives mixed in. Kowar has recorded 90 strikeouts at the MLB level, showing that his stuff can still miss bats and hinting at the raw ability that once made him a first-round selection. However, those strikeouts have not been enough to offset the traffic on the bases or the runs that have followed. The gap between his strikeout total and walk count underscores the inconsistency that has defined much of his time in the big leagues.
In many ways, Kowar’s career to this point is a reminder of how difficult the transition from amateur star to major league contributor can be. A strong pedigree and draft status can open doors, but sustained success at the highest level requires constant adjustment, refinement, and results.
Despite the rocky numbers, his continued opportunities suggest that teams still see potential in his arm and believe there may be a path forward with further development or a change in role.
While the promise that once surrounded Kowar has faded somewhat, his story is not yet finished. With experience across multiple seasons and organizations, he remains a pitcher searching for consistency and a chance to finally translate his early promise into major league success.
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