Australian Open · R64 · Hard · 18 Jan 2024
Katie Boulter v Qinwen Zheng
55–70 in points · Qinwen Zheng won
Why it went the way it did
Qinwen Zheng won 6.3 more points than Katie Boulter relative to what the serve alone predicted. Katie Boulter's biggest leaks: backhand execution −5.9, serve 1st execution −2.0, slice shot selection −1.3.
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 | Katie Boulter | Qinwen Zheng | ||||||
|---|---|---|---|---|---|---|---|---|
| Dir | Sel | Exec | Total | Dir | Sel | Exec | Total | |
| Serve 1st | ±0.0 | ±0.0 | −2.0 | −2.0 | +0.4 | ±0.0 | ±0.0 | +0.4 |
| Serve 2nd | ±0.0 | ±0.0 | +0.5 | +0.5 | +0.1 | ±0.0 | −1.2 | −1.1 |
| Return | −0.5 | −1.1 | +0.1 | −1.5 | −0.5 | ±0.0 | +0.1 | −0.4 |
| Forehand | +0.2 | +1.3 | +2.5 | +4.1 | −0.7 | +1.0 | +1.3 | +1.6 |
| Backhand | −0.5 | +0.7 | −5.9 | −5.8 | −0.2 | +0.4 | +1.5 | +1.8 |
| Slice | −0.3 | −1.3 | +0.2 | −1.3 | −0.1 | −1.2 | +0.2 | −1.1 |
| Net | −0.3 | −0.1 | +0.1 | −0.2 | +0.1 | +0.2 | −0.6 | −0.3 |
| Touch | +0.1 | +0.1 | +0.4 | +0.6 | ±0.0 | +0.1 | −0.1 | ±0.0 |
| All shots | −1.2 | −0.3 | −4.0 | −5.5 | −1.0 | +0.4 | +1.3 | +0.7 |
Set by set
| Set | Katie Boulter | Qinwen Zheng | Net, Katie | |
|---|---|---|---|---|
| 1 | −4.5 | −0.5 | −4.0 | |
| 2 | −1.0 | +1.3 | −2.2 |
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.
Katie Boulter serving
| Set | Wide | Body | T |
|---|---|---|---|
| 1 | 50% 33% | 23% 43% | 27% 63% |
| 2 | 54% 38% | 17% 75% | 29% 57% |
Set to set +1.69 per 100 first serves in sets 2+
Within sets +1.22 per 100 first serves, every two to three service games
Qinwen Zheng serving
| Set | Wide | Body | T |
|---|---|---|---|
| 1 | 43% 70% | 13% 33% | 43% 50% |
| 2 | 52% 64% | 6% 100% | 42% 45% |
Within sets +0.94 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.
Katie Boulter
6.2 points left on the table across 207 shots 3.01 per 100 shots
- Return +1: drive to your forehand side hit FH slice down the line ×3; FH slice crosscourt rates higher · 0.36 pts
- Return of a 2nd serve, wide, ad court hit BH through the middle ×7; BH crosscourt rates higher · 0.34 pts
- Rally, shots 5–8: drive to your backhand side hit BH through the middle ×7; BH crosscourt rates higher · 0.30 pts
- Rally, shots 5–8: drive to your middle hit BH through the middle ×6; BH crosscourt rates higher · 0.28 pts
Qinwen Zheng
7.1 points left on the table across 199 shots 3.58 per 100 shots
- Return of a 2nd serve, wide, deuce court hit FH through the middle ×5; FH inside-out rates higher · 0.57 pts
- Serve +1: deep return to your middle hit FH through the middle ×7; FH crosscourt rates higher · 0.42 pts
- Rally, shots 5–8: drive to your middle hit FH through the middle ×5; FH crosscourt rates higher · 0.35 pts
- Rally, shots 5–8: drive to your backhand side hit BH through the middle ×7; BH crosscourt rates higher · 0.30 pts