League Factors
How each level's run environment moves through the season. 100 is that level's season average, and a week above 100 had more of that result per plate appearance. The line is the model's calendar curve, with the same batters and pitchers all season. The dots are what each week actually produced. For each park's own pattern, see the Seasonal view of Park Factors.
Every stat, week by week
How it works
Scale: 100 is the level's average over that season, and each week is indexed to it. A week at 92 in home runs had 8% fewer home runs per plate appearance than the season as a whole. wOBA is per plate appearance and R is runs (BaseRuns) per plate appearance. AVG is hits per plate appearance, and 1B through HBP are each result per plate appearance. BACON is batting average on contact (home runs included) and wOBACon is wOBA on contact.
The line (model): the calendar curve of the Park Factors model's seasonal fit, which also gives the Seasonal view's "average" row there. The fit covers every plate appearance of MLB 2015–2026 and of AAA, AA, A+ and A 2021–2026. It has one curve per level, piecewise linear between points every two weeks from March 22 to October 4, with one shape for all seasons. Because the fit also has a term for each batter and each pitcher, the curve shows the environment with the same players all season: cold April air, summer heat and anything else that moves with the date for everybody. It also carries the mix of parks in use that week. Past years show the curve on that year's games and rates; 2027 shows it on the 2027 schedule.
The dots (actual): every plate appearance at the level that week, against the season, with no adjustment. They carry that year's weather and who played: September call-ups, injuries, promotions and demotions. A bigger dot has more plate appearances. A typical week has about 7,000, so chance alone moves home runs by about ±7 points and triples by about ±20. Opening weeks with a few games (the Tokyo and Seoul series) are small and noisy. Where the dots and the line part late in the season, the players changed, not the weather.
All years: the line is the newest year's (2027 for MLB, 2026 for the minors). The dots are every past season's weeks, and the table's Actual is their plate-appearance-weighted average, by date. Seasons without an April are left out, because their 100 is a summer-only average: MLB 2020 (60 games from late July) and the minors' 2021 season, which began in May. Pick the year to see them.
Colors: as on Park Factors, centered on 100 and saturated at 90 and 110. Red helps hitters and blue hurts them, so for K the scale is flipped. The table shows whole numbers; hold the pointer on a cell or a dot for one decimal.