US Open · F · Hard · 7 Sep 2019
Serena Williams v Bianca Andreescu
68–77 in points · Bianca Andreescu won
Why it went the way it did
Bianca Andreescu won 4.9 more points than Serena Williams relative to what the serve alone predicted. Serena Williams's biggest leaks: return execution −2.0, backhand execution −1.7, forehand execution −1.6.
Each shot moves its hitter's chance of winning the point. Those moves are split into direction choice, shot selection and execution, and summed here. Read both columns together: one player's gain is the other's loss.
| Shot | Serena Williams | Bianca Andreescu | ||||||
|---|---|---|---|---|---|---|---|---|
| Dir | Sel | Exec | Total | Dir | Sel | Exec | Total | |
| Serve 1st | +0.6 | ±0.0 | −0.2 | +0.4 | −0.6 | ±0.0 | +1.2 | +0.6 |
| Serve 2nd | ±0.0 | ±0.0 | −1.5 | −1.5 | ±0.0 | ±0.0 | −0.1 | ±0.0 |
| Return | +0.6 | ±0.0 | −2.0 | −1.5 | −0.3 | −0.1 | +0.4 | +0.1 |
| Forehand | ±0.0 | +1.1 | −1.6 | −0.5 | −0.1 | +0.9 | +3.6 | +4.4 |
| Backhand | +0.1 | +0.2 | −1.7 | −1.4 | −0.5 | +0.3 | −2.2 | −2.4 |
| Slice | +0.1 | −0.6 | +0.5 | ±0.0 | ±0.0 | −1.2 | −1.0 | −2.2 |
| Net | ±0.0 | +0.1 | +0.6 | +0.7 | ±0.0 | ±0.0 | +0.6 | +0.6 |
| Touch | −0.1 | −0.1 | −0.6 | −0.9 | +0.1 | −0.6 | −0.2 | −0.8 |
| All shots | +1.2 | +0.5 | −6.4 | −4.7 | −1.5 | −0.7 | +2.3 | +0.2 |
Set by set
| Set | Serena Williams | Bianca Andreescu | Net, Serena | |
|---|---|---|---|---|
| 1 | −0.8 | +2.7 | −3.5 | |
| 2 | −4.0 | −2.5 | −1.5 |
Adaptation
First-serve direction mix set by set, with the share of points each direction won. The scores measure whether the server moved toward the directions that had been winning earlier in this match, set to set and every two to three service games, in points per 100 first serves. Read them as a habit, not a gain: across the tour, a direction's edge in early sets barely predicts the later ones. Whether the returner responded can't be told apart from noise within one match.
Serena Williams serving
| Set | Wide | Body | T |
|---|---|---|---|
| 1 | 55% 59% | 3% 0% | 43% 53% |
| 2 | 49% 47% | 3% 0% | 49% 41% |
Set to set −0.17 per 100 first serves in sets 2+
Within sets +0.86 per 100 first serves, every two to three service games
Bianca Andreescu serving
| Set | Wide | Body | T |
|---|---|---|---|
| 1 | 24% 67% | 36% 78% | 40% 60% |
| 2 | 23% 50% | 40% 35% | 37% 63% |
Within sets +0.07 per 100 first serves, every two to three service games
Counterfactual: the best direction every time
If each shot had gone in the direction that is usually worth most for that stroke and position, this is how many more points each player would expect to win. It's an upper bound: the best direction isn't always on, and the chart can't see the ball's pace or position.
Serena Williams
4.2 points left on the table across 198 shots 2.12 per 100 shots
- Rally, shots 5–8: drive to your middle hit FH through the middle ×5; FH crosscourt rates higher · 0.35 pts
- Serve +1: mid-depth return to your middle hit BH through the middle ×4; BH crosscourt rates higher · 0.25 pts
- Rally, shots 5–8: drop shot to your backhand side, opponent at net hit BH through the middle ×1; BH crosscourt rates higher · 0.20 pts
- Serve +1: short return to your middle hit FH through the middle ×2; FH down the line rates higher · 0.19 pts
Bianca Andreescu
5.4 points left on the table across 186 shots 2.89 per 100 shots
- Return of a 2nd serve, body, deuce court hit BH through the middle ×8; BH crosscourt rates higher · 0.36 pts
- Rally, shots 5–8: drive to your backhand side hit BH through the middle ×7; BH crosscourt rates higher · 0.30 pts
- Serve +1: mid-depth return to your middle hit FH through the middle ×3; FH crosscourt rates higher · 0.25 pts
- Serve +1: mid-depth return to your middle hit BH through the middle ×4; BH crosscourt rates higher · 0.25 pts