A tactical debate is heating up in Seattle.
While many MLB teams are trying to optimize pitching rotation in the traditional way or with six-man rotation, a less popular idea continues to be strongly defended: the “piggyback starter” model — where two pitchers share a pitching run.
And according to the latest analysis by MLB Network journalist Jon Morosi, this remains the most logical option for the Seattle Mariners at the moment.
In the piggyback model, two pitchers share a pitching run: one starts, the other follows immediately to extend the innings, instead of using a traditional bullpen or relying entirely on a starter for 6–7 innings.
This tactic has been controversial, but it offers great flexibility for teams with inconsistent rotation or those managing a workload for young pitchers.
And for the Seattle Mariners, Morosi believes this isn’t an experiment—it’s “the best solution in the current circumstances.”
According to experts, Seattle’s biggest problem isn’t the bullpen, but the consistency of the rotation.
Some starters have the ability to dominate, but lack the consistency to sustain innings throughout a 162-game season.
Piggyback solves several problems simultaneously:
Reducing pressure on underdeveloped starters
Limiting “third time through the order penalty” issues
Optimizing pitcher-batter matchups
Keeping the bullpen less overloaded
This is especially important during the Mariners’ fierce competition in the American League.
Jon Morosi emphasizes that while the initial results of this model aren’t always perfect, the strategic essence remains clear: the Mariners are seeking to maximize pitching performance while protecting the health of their young pitchers.
He argues that breaking down the workload isn’t just a short-term solution, but a way for the team to maintain competitiveness throughout the long season.
In modern baseball, where data and workload management are increasingly important, piggybacking is no longer a “novel idea,” but is becoming a real tactical tool.
One of the most notable points is how the Mariners apply this model to key pitchers like Bryce Miller and Luis Castillo.
Instead of requiring them to carry the entire game, the team tends to split innings to:
increase performance per pitching run
reduce the risk of fatigue
and maintain more consistent pitch quality in the late season
This approach helps Seattle maintain strong rotation without sacrificing long-term durability.
Despite Morosi’s praise, the piggyback model remains controversial among fans and analysts.
Some argue that:
It disrupts the pitcher’s natural rhythm
Makes it difficult to establish clear roles
And diminishes the value of the “true ace” in rotation
There are even concerns that this model is only suitable for temporary periods, not as a long-term foundation.
What keeps Seattle steadfast in this model is the reality of their roster.
They don’t possess a completely stable rotation sufficient to:
guarantee 6–7 innings per start
or maintain high performance throughout the season
In that context, piggyback becomes a “balancing solution” between:
short-term performance
and long-term management
The bigger picture: MLB is changing how pitchers are used
It’s worth noting that the Mariners aren’t the only team experimenting with this approach.
The entire MLB is witnessing a shift:
from extended starters to openers
from 5-man rotation to flexible rotations
from fixed workloads to data-driven usage
Piggyback is just one part of a larger trend: redefining the pitcher’s role in modern baseball.
Despite its controversial nature, the Mariners’ piggyback rotation isn’t reckless—it’s a calculated form of risk management.
In Jon Morosi’s eyes, it remains the best option for Seattle right now: a team that needs to balance playoff ambitions with the sustainability of its pitching staff.
And if this system continues to work effectively, the Mariners may be ahead of the rest of MLB in redefining the role of a modern rotation.
Not traditional.
Not a complete breakthrough.
But a tactical hybrid that is becoming the future.
