US Open · QF · Hard · 2 Sep 2014
Caroline Wozniacki v Sara Errani
57–26 in points · Caroline Wozniacki won
Why it went the way it did
Caroline Wozniacki won 14.6 more points than Sara Errani relative to what the serve alone predicted. Sara Errani's biggest leaks: slice shot selection −2.5, forehand direction choices −1.5, net execution −1.0.
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 | Caroline Wozniacki | Sara Errani | ||||||
|---|---|---|---|---|---|---|---|---|
| Dir | Sel | Exec | Total | Dir | Sel | Exec | Total | |
| Serve 1st | +0.2 | ±0.0 | +1.1 | +1.2 | −0.5 | ±0.0 | +0.4 | ±0.0 |
| Serve 2nd | ±0.0 | ±0.0 | −0.2 | −0.2 | ±0.0 | ±0.0 | +0.4 | +0.4 |
| Return | ±0.0 | +0.4 | +3.4 | +3.8 | ±0.0 | +0.4 | +2.9 | +3.2 |
| Forehand | −0.9 | +1.1 | +5.5 | +5.7 | −1.5 | +2.8 | +3.4 | +4.7 |
| Backhand | +0.1 | +0.9 | +8.2 | +9.2 | −0.5 | +1.1 | ±0.0 | +0.6 |
| Slice | ±0.0 | −1.1 | +0.5 | −0.6 | −0.4 | −2.5 | −0.6 | −3.4 |
| Net | ±0.0 | ±0.0 | +0.6 | +0.6 | −0.2 | +0.2 | −1.0 | −1.0 |
| Touch | −0.1 | −0.1 | ±0.0 | −0.2 | +0.1 | +0.3 | +0.2 | +0.5 |
| All shots | −0.8 | +1.1 | +19.1 | +19.5 | −3.1 | +2.3 | +5.6 | +4.9 |
Set by set
| Set | Caroline Wozniacki | Sara Errani | Net, Caroline | |
|---|---|---|---|---|
| 1 | +11.8 | +3.3 | +8.4 | |
| 2 | +7.7 | +1.6 | +6.1 |
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.
Caroline Wozniacki serving
| Set | Wide | Body | T |
|---|---|---|---|
| 1 | 50% 80% | 5% 100% | 45% 56% |
| 2 | 38% 55% | 17% 60% | 45% 62% |
Within sets −0.72 per 100 first serves, every two to three service games
Sara Errani serving
| Set | Wide | Body | T |
|---|---|---|---|
| 1 | 47% 44% | 32% 17% | 21% 0% |
| 2 | 20% 33% | 67% 20% | 13% 0% |
Within sets +2.75 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.
Caroline Wozniacki
7.5 points left on the table across 272 shots 2.77 per 100 shots
- Rally, shots 5–8: drive to your middle hit FH through the middle ×8; FH crosscourt rates higher · 0.56 pts
- Rally, shots 5–8: drive to your forehand side hit FH through the middle ×9; FH crosscourt rates higher · 0.49 pts
- Long rally, 9+: drive to your forehand side hit FH through the middle ×8; FH crosscourt rates higher · 0.44 pts
- Long rally, 9+: drive to your middle hit BH through the middle ×8; BH down the line rates higher · 0.44 pts
Sara Errani
9.9 points left on the table across 281 shots 3.51 per 100 shots
- Rally, shots 5–8: drive to your middle hit FH through the middle ×12; FH crosscourt rates higher · 0.84 pts
- Long rally, 9+: drive to your forehand side hit FH through the middle ×12; FH crosscourt rates higher · 0.66 pts
- Long rally, 9+: drive to your backhand side hit BH through the middle ×10; BH crosscourt rates higher · 0.52 pts
- Rally, shots 5–8: drive to your forehand side hit FH through the middle ×9; FH crosscourt rates higher · 0.49 pts