Does Opening Day Predict the Season?

Seattle Mariners opener results vs. full-season win percentage, 1977–2025

30
seasons won opener
47.9%
avg season W%
19
seasons lost opener
47.5%
avg season W%
+0.4 pp
W% advantage
when winning opener
49
seasons
analyzed
Did the opener result predict a winning or losing season?
Season Win % by Opener Result
Year Opener Result Score Season W-L Win%
1977 vs California Angels L 0–7 64–98 39.5%
1978 vs Minnesota Twins W 3–2 56–104 (160g) 35.0%
1979 vs California Angels W 5–4 67–95 41.4%
1980 vs Toronto Blue Jays W 8–6 59–103 36.4%
1981 vs California Angels L 2–6 45–65 (110g) 40.9%
1982 @ Minnesota Twins W 11–7 76–87 (163g) 46.6%
1983 vs New York Yankees W 5–4 60–102 37.0%
1984 vs Toronto Blue Jays W 3–2 74–88 45.7%
1985 vs Oakland Athletics W 6–3 74–88 45.7%
1986 vs California Angels W 8–4 67–95 41.4%
1987 @ California Angels L 1–7 78–84 48.1%
1988 @ Oakland Athletics L 1–4 68–93 (161g) 42.2%
1989 @ Oakland Athletics L 2–3 73–89 45.1%
1990 @ California Angels W 7–4 77–85 47.5%
1991 vs California Angels L 2–3 83–79 51.2%
1992 vs Texas Rangers L 10–12 64–98 39.5%
1993 vs Toronto Blue Jays W 8–1 82–80 50.6%
1994 @ Cleveland Indians L 3–4 49–63 (112g) 43.8%
1995 vs Detroit Tigers W 3–0 79–66 (145g) 54.5%
1996 vs Chicago White Sox W 3–2 85–77 52.5%
1997 vs New York Yankees W 4–2 90–72 55.6%
1998 vs Cleveland Indians L 9–10 76–85 (161g) 47.2%
1999 vs Chicago White Sox L 2–8 79–83 48.8%
2000 vs Boston Red Sox L 0–2 91–71 56.2%
2001 vs Oakland Athletics W 5–4 116–46 71.6%
2002 vs Chicago White Sox L 5–6 93–69 57.4%
2003 @ Oakland Athletics L 0–5 93–69 57.4%
2004 vs Anaheim Angels L 5–10 63–99 38.9%
2005 vs Minnesota Twins W 5–1 69–93 42.6%
2006 vs Los Angeles Angels L 4–5 78–84 48.1%
2007 vs Oakland Athletics W 4–0 88–74 54.3%
2008 vs Texas Rangers W 5–2 61–101 37.7%
2009 @ Minnesota Twins W 6–1 84–77 (161g) 52.2%
2010 @ Oakland Athletics W 5–3 61–101 37.7%
2011 @ Oakland Athletics W 6–2 66–94 (160g) 41.3%
2012 @ Oakland Athletics W 3–1 75–86 (161g) 46.6%
2013 @ Oakland Athletics W 2–0 71–91 43.8%
2014 @ Los Angeles Angels W 10–3 87–75 53.7%
2015 vs Los Angeles Angels W 4–1 76–86 46.9%
2016 @ Texas Rangers L 2–3 86–76 53.1%
2017 @ Houston Astros L 0–3 78–84 48.1%
2018 vs Cleveland Indians W 2–1 89–72 (161g) 55.3%
2019 @ Oakland Athletics W 9–7 68–94 42.0%
2020 @ Houston Astros L 2–8 27–33 (60g) 45.0%
2021 vs San Francisco Giants W 8–7 91–72 (163g) 55.8%
2022 @ Minnesota Twins W 2–1 90–72 55.6%
2023 vs Cleveland Guardians W 3–0 88–74 54.3%
2024 vs Boston Red Sox L 4–6 85–77 52.5%
2025 vs Athletics W 4–2 90–72 55.6%

Data: MLB Stats API · Regular season games only