For a segment of Seattle Mariners fans, last season’s negative run differential is irrelevant. The team finished with 90 wins and contended for the postseason until game-162. Who cares about some meaningless metric created by nerds?

Run Differential is determined by subtracting a team’s runs allowed from its runs scored

Well, I can’t speak for other nerds. But this dumb baseball blogger views run differential as a reflection of a team’s actual capabilities. In the case of the 2021 Mariners, that “meaningless metric” should serve as a bellwether to potential fan disappointment in 2022.

The run differential naysayers are correct when they say the Mariners had a great year. But those 90 wins have duped a portion of a playoff-starved fan base into believing the team is ready to repeat last year’s success. Unfortunately, Seattle’s -51 run differential paints a bleaker picture for the upcoming season.

Sure, what the Mariners accomplished last season was fun and exhilarating. But being so successful with such a negative run differential is a statistical anomaly not likely to be repeated in 2022. Consider this fact; only four teams with a negative run differential have ever won 90-plus games in a season. None had a run differential below -30 until Seattle earned that dubious distinction last year.

Best W-L Records With A Negative Run Differential
1997 Giants (90-72, -9 run differential)
2007 Diamondbacks (90-72, -20 run differential)
1985 Mets (90-72, -24 run differential)
2021 Mariners (90-72, -51 run differential)

In reality, Seattle’s extremely negative run differential suggests the team overachieved in a big way in 2021.

The Pythagorean What?

According to the Pythagorean winning percentage formula developed by Bill James, the 90-72 Mariners were closer to a 76-86 club. That’s the same number of wins tallied in 2015 when Seattle parted ways with former GM Jack Zduriencik and hired current GM Jerry Dipoto. This seems relevant for an organization trying to snap a decades-long postseason drought.

And how exactly is James’ formula calculated?

Plug a team’s runs allowed and runs scored into an equation that you probably don’t care about. Therefore, I won’t belabor the inner workings of how the sausage is made.

Bottom line: the Pythagorean formula estimates a team’s winning percentage based on its runs allowed and runs scored (the components of run differential).

If you happen to prefer knowing more about the numbers you’re consuming, I suggest you check out the page Baseball Reference has devoted to explaining what drives the Pythagorean formula.

Can’t We Just Ignore May?

Those quick to dismiss the Mariners’ awful -51-run differential often point to the fact that most of that negativity was generated in one month. That is true. The club allowed 43 more runs than it scored in May.

During that challenging month, Mariner hitters had an MLB-worst .199 AVG with the team being no-hit twice in a 12-game span. Compounding matters, the pitching staff also stumbled with a 25th ranked 4.89 ERA. Clearly, June could not come quick enough for manager Scott Servais and crew.

Ninja Column 1Ninja Column 2Ninja Column 6Ninja Column 7Ninja Column 8
M's W-L Record By Month (2021)
W-L
RDiff
W-L%
Pythag W-L%
Apr
15-12
1
.556
.504
May
13-15
-43
.464
.337
Jun
14-12
-5
.538
.482
Jul
14-10
-8
.583
.468
Aug
15-13
-2
.536
.492
Sep/Oct
19-10
6
.655
.520
Yr
90-72
-51
.555
.468

Although May was a particularly difficult month for Servais’ hitters and pitchers, we should keep things in perspective. Despite those two no-hitters and suboptimal pitching, the Mariners managed to win 13 of 28 contests. It’s also worth noting that Seattle had a negative run differential in every month with the exception of April and September.

Even if we omitted May’s data from the equation, the Mariners still would’ve had a negative run differential and a sub-.500 Pythagorean winning percentage for the season. Just for fun, I compiled the following to illustrate this point.

Ninja Column 1Ninja Column 2Ninja Column 5Ninja Column 6
M's Season With & Without May Included
W-L
W-L%
Pythag W-L%
Full Season
90-72
.555
.468
Season w/o May
77-57
.575
.494

Granted, the Mariners’ actual winning percentage and run differential would’ve looked much better if we could magically erase May from the picture. But that’s not how baseball works. Seattle’s most challenging month last season counts as much as September when the team peaked.

Oh, Those One-Run Games

Anyone familiar with the Mariners knows the team was very good in games decided by one run last year. Servais’ squad played in an AL-leading 52 one-run games posting a 33-19 record that translated to a .635 winning percentage. This good fortune played a central role in the team winning 90 games despite an unsightly run differential. Still, success in one-run contests is somewhat fleeting from year to year.

Since the Mariners last postseason appearance in 2001 through the 2018 campaign, 62 teams have boasted a winning percentage of .600 or better in one-run games. Nine managed to repeat that success the following year, although a vast majority significantly regressed.

Over half of those 62 clubs (33), didn’t have a winning record the next year with 44 seeing at least a .100 drop in winning percentage. Such a reduction would’ve cost the Mariners five wins in 2021. While an 85-win campaign would’ve been okay last year, that outcome would’ve deprived fans and players of the electric atmosphere they experienced at T-Mobile Park during that final weekend of the season.

Could the Mariners repeat their one-run success this year?

Sure, but history isn’t on Seattle’s side.

But The Blowouts!

Last season, only the Orioles (.228) had a worse winning percentage in games decided by five-plus runs (blowouts) than the Mariners (.282). This continued a trend for Seattle, which had a .300 winning percentage in blowouts during the truncated 2020 campaign.

Remember how bad May was for Servais’ unit? It turns out that the team had an awful record in blowout games that month. That said, June wasn’t much better.

Ninja Column 1Ninja Column 2Ninja Column 3Ninja Column 4Ninja Column 6
M's One-Run & Blowout Game Success by Month
W-LOne-Run W-LBlowout W-LRDiff
Apr
15-12
7-4
2-3
1
May
13-15
6-1
1-7
-43
Jun
14-12
5-2
2-7
-5
Jul
14-10
5-2
1-4
-8
Aug
15-13
4-7
2-3
-2
Sep/Oct
19-10
6-3
3-4
6
Year
90-72
33-19
11-28
-51

To be clear, success in blowout games doesn’t necessarily guarantee success in the standings. That said, nine of the ten teams with the highest winning percentage in blowouts in 2021 reached the postseason. The only top-10 club missing out of meaningful October baseball was Toronto. The Cardinals, an NL wild card, ranked 14th with a 24-24 record in blowouts.

Obviously, better blowout success would help the Mariners’ run differential. More importantly though, improving in this area may help mitigate any potential decline in one-run game success.

ZiPS Says

It’s not just me who’s referring to the Mariners’ 2021 negative run differential as a potential red flag heading into the upcoming season. According to FanGraphs’ Zymborski Projection System (ZiPS), Seattle projects to win 80 games this year. That’s just four more victories than last year’s Pythagorean estimate.

When ZiPS creator Dan Szymborski recently joined The Mike Salk Show on 710 ESPN Seattle to discuss how his system assessed the Mariners’ outlook, he repeatedly mentioned last year’s negative run differential as a contributing factor to a suboptimal 2022 projection that shocked some fans.

“One of the things is that baseball history is a little cruel to teams who overperform their runs scored and runs allowed. That tends to be a better predictor of future performance.” – Dan Szymborski, FanGraphs

Note: Brent Stecker of 710Sports.com did a great job of recapping Szymborski’s segment with host Mike Salk in a follow-up article that includes audio of the full conversation.

It’s important to note Szymborski emphasized that the Mariners’ roster likely morphs after the MLB lockout ends around Memorial Day. Assuming the front office makes necessary adjustments prior to Opening Day, future iterations of ZiPS should view the team in a better light.

Parting Words

Realistically, run differential isn’t an iron-clad metric. But my takeaway from the Mariners being outscored by 51 runs is the roster overachieved last year thanks to the talent and determination of players and their belief in one another.

Having said that, Dipoto and staff must add proven bats (plural) to the lineup, an established arm to the starting staff, plus enhanced positional and rotational depth. Otherwise, the Mariners risk regressing from last season’s 90-win tally and continuing their postseason drought into 2023.

That would be so disappointing after the Mariners provided fans with so many thrills last September. Such a scenario would also drag down the team’s fun differential in 2022.

And nobody wants that.

My Oh My…

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Luke Arkins

Luke is a native New Yorker, who grew up as a Mets fan. After the US Navy moved him to the Pacific Northwest in 2009, he decided to make Seattle his home. In 2014, Luke joined the Prospect Insider team. During baseball season, he can often be found observing the local team at T-Mobile Park. You can follow Luke on Twitter @luke_arkins

2 Comments

  1. Author

    No stat is predictive.

  2. A year later and this post begs for this familiar disclaimer: “Past performance is not indicative of future results”. That’s especially true when a ballclub improves its starting pitching in the remarkable way that Jerry Dipoto did this year.

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