US Open · R32 · Hard · 30 Aug 1991
John Mcenroe v Michael Chang
167–174 in points · Michael Chang won
Why it went the way it did
Michael Chang won 5.2 more points than John Mcenroe relative to what the serve alone predicted. John Mcenroe's biggest leaks: net execution −6.9, backhand execution −1.4, serve 1st execution −1.1.
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 | John Mcenroe | Michael Chang | ||||||
|---|---|---|---|---|---|---|---|---|
| Dir | Sel | Exec | Total | Dir | Sel | Exec | Total | |
| Serve 1st | −0.3 | +3.5 | −1.1 | +2.0 | +0.2 | −2.7 | −0.4 | −2.9 |
| Serve 2nd | −0.3 | +2.1 | +0.2 | +2.0 | +0.1 | −1.5 | +3.0 | +1.7 |
| Return | ±0.0 | +4.8 | +4.8 | +9.7 | +0.1 | +2.1 | +1.6 | +3.8 |
| Forehand | +0.2 | +3.3 | +0.7 | +4.3 | −1.1 | +4.5 | −2.7 | +0.7 |
| Backhand | −0.3 | +1.4 | −1.4 | −0.2 | +0.5 | +2.8 | +8.9 | +12.2 |
| Slice | +0.2 | −0.5 | +0.4 | ±0.0 | −0.1 | ±0.0 | +0.1 | +0.1 |
| Net | −0.3 | +1.5 | −6.9 | −5.8 | −0.6 | +0.5 | −1.4 | −1.5 |
| Touch | ±0.0 | −0.6 | −0.3 | −1.0 | −0.3 | −3.1 | +5.5 | +2.1 |
| All shots | −0.8 | +15.5 | −3.7 | +11.0 | −1.1 | +2.7 | +14.6 | +16.2 |
Set by set
| Set | John Mcenroe | Michael Chang | Net, John | |
|---|---|---|---|---|
| 1 | +0.2 | +5.0 | −4.8 | |
| 2 | +2.8 | +0.5 | +2.4 | |
| 3 | −0.5 | +1.4 | −1.8 | |
| 4 | +6.1 | +3.4 | +2.6 | |
| 5 | +2.3 | +5.9 | −3.5 |
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.
John Mcenroe serving
| Set | Wide | Body | T |
|---|---|---|---|
| 1 | 52% 50% | 21% 33% | 26% 45% |
| 2 | 47% 47% | 16% 60% | 38% 83% |
| 3 | 50% 38% | 6% 0% | 44% 57% |
| 4 | 44% 67% | 12% 0% | 44% 73% |
| 5 | 46% 83% | 12% 67% | 42% 27% |
Set to set −0.03 per 100 first serves in sets 2+
Within sets +0.76 per 100 first serves, every two to three service games
Michael Chang serving
| Set | Wide | Body | T |
|---|---|---|---|
| 1 | 36% 54% | 3% 100% | 61% 55% |
| 2 | 32% 50% | 13% 75% | 55% 53% |
| 3 | 40% 25% | 10% 0% | 50% 80% |
| 4 | 29% 71% | 8% 0% | 63% 47% |
| 5 | 30% 60% | – | 70% 74% |
Set to set +0.41 per 100 first serves in sets 2+
Within sets +0.44 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.
John Mcenroe
20.2 points left on the table across 381 shots 5.30 per 100 shots
- Serve +1: drive to your forehand side, you at net hit FH volley through the middle ×5; FH volley crosscourt rates higher · 1.23 pts
- Serve +1: short return to your middle, you at net hit FH volley through the middle ×4; FH volley crosscourt rates higher · 0.99 pts
- Serve +1: drive to your middle, you at net hit FH volley down the line ×16; FH volley crosscourt rates higher · 0.78 pts
- Rally, shots 5–8: drive to your middle, you at net hit BH volley through the middle ×3; BH volley crosscourt rates higher · 0.65 pts
Michael Chang
19.2 points left on the table across 416 shots 4.61 per 100 shots
- Return of a 1st serve, wide, ad court, server rushing the net hit BH through the middle ×16; BH crosscourt rates higher · 1.24 pts
- Rally, shots 5–8: volley to your forehand side, opponent at net hit FH through the middle ×3; FH crosscourt rates higher · 0.71 pts
- Return of a 2nd serve, body, deuce court, server rushing the net hit BH through the middle ×4; BH crosscourt rates higher · 0.63 pts
- Return +1: volley to your forehand side, opponent at net hit FH lob through the middle ×5; FH lob crosscourt rates higher · 0.60 pts