ATP · Left-handed · 4 charted matches · 1995–1998
Jan Siemerink
Against an average opponent
Serve and return points won, refitted against every opponent at once so a record built on weak or strong opposition is put on the same scale. Career, all surfaces, with a 90% margin. Raw is the plain share of points won.
Shot expected value
The share of points Jan Siemerink goes on to win after each option in the positions they face most often, shrunk toward tour average when the sample is small. Showing the 8 most-used options; teal marks the best one with at least 30 shots.
Serve +1: drive to your middle, you at net
position worth 61% to the average player · 56 shots
| Option | Used | Win % | Tour |
|---|---|---|---|
| BH volley crosscourt | 34% | 60.5%±12.9 | 62.9% |
| FH volley crosscourt | 20% | 66.9%±13.9 | 68.7% |
| FH volley down the line | 18% | 55.9%±14.9 | 63.8% |
Return +1: drive to your backhand side
position worth 44% to the average player · 39 shots
| Option | Used | Win % | Tour |
|---|---|---|---|
| BH slice crosscourt | 36% | 38.8%±13.7 | 40.9% |
| BH slice through the middle | 31% | 23.5%±12.3 | 32.6% |
Serve under pressure
Deuce court
| 1st serve | Usage | Break pt | Won when in |
|---|---|---|---|
| Wide | 43% | 50% | 81% / 73% |
| Body | 11% | 25% ▲ | 65% / 63% |
| T | 46% | 25% ▼ | 76% / 75% |
209 normal · 4 break-point 1st serves
Ad court
| 1st serve | Usage | Break pt | Won when in |
|---|---|---|---|
| Wide | 48% | 42% | 74% / 73% |
| Body | 13% | 26% ▲ | 57% / 63% |
| T | 39% | 32% | 78% / 72% |
180 normal · 19 break-point 1st serves
Is the serve mix in equilibrium?
Game theory says a well-mixed server wins equally often with every direction they use. If one direction wins more, it's underused and points are being left behind. This is the minimax test Walker and Wooders ran on Wimbledon finals, applied to every charted first serve. Win rates include faults. "Optimal" allows for returners reading a habit. No measurable response (−0.05 ± 0.15 points per 100 serves for every 10 points of habitual usage), measured from ATP servers whose mix drifted between matches. Shifts stay within the range servers' habits actually vary, the only range that response was measured over.
Deuce court
| 1st serve | Usage | Points won | Optimal |
|---|---|---|---|
| Wide | 43% | 68.4%±6.9 n=92 | 56% ▲ |
| Body | 11% | 64.1%±10.7 n=24 | 0% ▼ |
| T | 46% | 65.0%±7.0 n=97 | 44% ▼ |
Consistent with an optimal mix (p = 0.69).
Optimal mix: +0.7 per 100 first serves.
Ad court
| 1st serve | Usage | Points won |
|---|---|---|
| Wide | 47% | 62.6%±7.1 n=94 |
| Body | 15% | 53.3%±10.7 n=29 |
| T | 38% | 64.3%±7.7 n=76 |
Consistent with an optimal mix (p = 0.13).
Exploitability 0.72 points per 100 first serves What the optimal mix would win over the current one, both courts. More exploitable than 100% of ATP servers. Tested on matches they weren't fitted on, ATP mixes picked this way win 0.33 per 100 first serves on average.
Repeating the previous direction to the same court: +1.3±8.6 points per 100 against switching. Negative means returners read repeats. Tour-wide, repeating costs women about 0.4 points per 100 and costs men nothing, so men's returners don't measurably anticipate direction. (163 repeats, 241 switches.)
Return by serve direction
Return points won against each serve direction, compared with the tour average.
| Serve | Court | Direction | Points | Won | vs tour | |
|---|---|---|---|---|---|---|
| 1st | Ad court | Body | 7 | 38% | +1.1±13.1 | |
| 1st | Ad court | T | 47 | 23% | −5.4±7.8 | |
| 1st | Ad court | Wide | 61 | 12% | −15.0±5.7 | |
| 1st | Deuce court | Body | 4 | 32% | −4.3±13.2 | |
| 1st | Deuce court | T | 47 | 19% | −6.2±7.3 | |
| 1st | Deuce court | Wide | 70 | 23% | −4.0±6.9 | |
| 2nd | Ad court | Body | 22 | 44% | −5.5±11.3 | |
| 2nd | Ad court | T | 33 | 50% | +1.2±10.4 | |
| 2nd | Ad court | Wide | 17 | 46% | −2.6±12.0 | |
| 2nd | Deuce court | Body | 18 | 43% | −5.9±11.8 | |
| 2nd | Deuce court | T | 17 | 49% | −1.0±12.0 | |
| 2nd | Deuce court | Wide | 48 | 45% | −2.7±9.3 |
Signature patterns
Recurring sequences that win more than Jan Siemerink's own baseline, ranked by edge weighted by how often they're used.
Serve → +1
- Not enough data
Return
- vs wide serve (deuce court) → BH slice through the middle, mid used 40.4% · won 23% · +0.3±9.4 vs own baseline
Rally, consecutive own shots
- Not enough data