So How Did I Get That Rating?
BAL ratings are usually calculated after about one-third and two-thirds of the current season's schedule is complete — typically after Round 5 and Round 10 — and once again at the end of the season (including the playoffs). Thus each season usually has three rating cycles.
- Within a rating cycle, games won by forfeit are not counted for rating purposes.
- For rating purposes, new, unrated players with Captain's Estimate (CE) ratings are assumed to have an initial rating of 1300 based on zero previous games.
Within a rating cycle, performance ratings are first calculated for all new, unrated players. These performance ratings are then used when calculating the ratings of the remaining (non-CE) players.
Provisional Ratings Calculation
The provisional rating calculation formula is:(np × Rp) + ( ∑ Ro ) + (400 × ( ∑ W - ∑ L)) |
||
| G = |
np + nc |
- Rp |
where
G is
the gain in rating (can be negative),
np is the number of games
played prior to the ratings cycle,
Rp is the player's previous rating,
∑ Ro is the sum of the ratings of the player's opponents,
∑ W is the sum of the player's wins (win = 1, draw = 0.5),
∑ L is the sum of the player's losses (loss = 1, draw = 0.5), and
nc is the number of games played in this ratings cycle
Rp is the player's previous rating,
∑ Ro is the sum of the ratings of the player's opponents,
∑ W is the sum of the player's wins (win = 1, draw = 0.5),
∑ L is the sum of the player's losses (loss = 1, draw = 0.5), and
nc is the number of games played in this ratings cycle
Established Ratings Calculation
The established rating calculation is a bit more complex:| G = | k × ( ∑W - ∑We ) |
where
G
is the gain in rating (can be negative),
k is a constant based on the player's previous rating (16 if over 2399, 24 if between 2100 and 2399, and 32 otherwise),
∑W is the sum of the player's game scores (win = 1, loss = 0, draw = 0.5), and
∑We is the sum of the player's "expected wins" against each opponent, computed for each opponent as:
k is a constant based on the player's previous rating (16 if over 2399, 24 if between 2100 and 2399, and 32 otherwise),
∑W is the sum of the player's game scores (win = 1, loss = 0, draw = 0.5), and
∑We is the sum of the player's "expected wins" against each opponent, computed for each opponent as:
| 1 |
|
| We = |
1 + 10 - (Δr ÷ 400) |
where Δr is the difference between the
player's and opponent's rating.
K-Adjustment
After the appropriate calculation is performed, the resulting gain may be adjusted if the player's new rating crosses one of the "k" boundaries as follows ( RO = old rating, RN= new rating):If (either RO or RN) > 2099
If
((both RO and RN) ≥ 2400) OR (2100 ≤ (both RO and RN) ≤ 2400)
ElseRN
is not changed
ElseIf (RO < 2100)RN
= 2100 + (RN - 2100) × 0.75
ElseIf RO < 2400If
RN < 2100
ElseIf RO ≥ 2400RN
= 2100 + (RN - 2100) × 1.33
ElseIf RN > 2399RN
= 2400 + (RN - 2400) × 0.66
ElseRN
is not changed
If
RN < 2400
RN = 2400 + (RN - 2400) × 1.50
ElseRN
is not changed
RN
is not changed