Mariners: How Much of a Concern Is Last Year’s Run Differential?

In 2021, the Seattle Mariners culminated a magically strange season with 90 wins (their highest total since 2003) while surrendering 51 more runs than they scored themselves. It was a phenomenal feat that led to satirical observations by manager Scott Servais that the Mariners, despite their massive negative run differential, were the league leader in “fun differential”. Yes, the 2021 season was fun – but was it a sustainable strategy for success heading into next season?

On the rare occasion that a team is able to conjure 90 wins and a near-playoff berth while giving up far more runs than they’ve scored, there are always a couple of factors at play: the team is winning close games (due to a decent starting rotation and stout bullpen), and losing blowout games (due to a heavily inconsistent offense).

If the Seattle Mariners want to be successful in 2022, they will need similar production from last season’s pitching staff and a much improved offense.

While last year’s Mariners bullpen was stingy (4th best in the American League), there’s no guarantee that hidden gems Casey Sadler, Paul Sewald, and Drew Steckenrider will be able to repeat their dominance next season. More proven arms such as Diego Castillo and Ken Giles will be joining the fray, but the effectiveness of the bullpen will need to be closely monitored in Spring Training to get a feel for just how productive the offense will need to be.

On offense, the Mariners added All-Star utility player Adam Frazier this offseason, but they lost middle-of-the-order staple Kyle Seager to retirement; considering that interchange of talent, the team doesn’t project to be improved on an offensive front yet. However, JP Crawford and Ty France are expected to continue to improve, and young star Jarred Kelenic has the potential to develop into a legitimate threat in the heart of the batting order.

If Seattle wants to hedge their bet of getting a repeat performance from their starting rotation and bullpen next year, and of significant improvement from their young contributors, it will be absolutely necessary for them to acquire one or two more impact bats once the offseason resumes. Otherwise, another year with a negative run differential might not turn out to be so fun.