RallyIQ

Game plan

Simona Halep v Sara Errani

Every number combines what Simona Halep does well with what Sara Errani allows, each measured against the tour average and shrunk toward it when the sample is thin. Flip perspective

Forecast

Simona Halep wins, best of 3 92%90%: 56%–100% · best of 5: 96%
Serve points won 57.5% / 46.9% Simona / Sara · tour 58.1%
Strengths only, no similarity priors 91%serve 57.2% / 47.3%

Each player's serve and return strength is fitted against every opponent they were charted against, so a record built on weak opponents counts for less. At least one of them is no longer active or has too little charted in the last three seasons, so both are compared on their careers. The result is then nudged by Simona Halep's record against Sara Errani's tactical lookalikes and in their charted head-to-heads (lookalikes: +8.7 on serve, +10.6 on return vs expectation (105 points)). A game-by-game Markov chain turns point odds into match odds; the 90% range covers the uncertainty in the two strengths, not the nudges. Charted matches lean toward big events, so treat this as a scouting estimate, not a betting line.

Head to head, per 100 shots

CareerSimonaSara
Direction choice+0.06 ±0.12
better than 65%
−0.23 ±0.11
better than 14%
Shot selection+0.40 ±0.18
better than 90%
−0.34 ±0.17
better than 19%
Execution+0.32 ±0.60
better than 74%
+1.67 ±0.48
better than 97%
Points left on the table2.41 ±0.24
lower than 76%
2.62 ±0.13
lower than 48%

Each player's career against an average tour player in the same position, adjusted for opponent strength, with a 90% margin (shots clustered by match). Points left on the table is the gap to the best-value direction for the same stroke, so lower is better. Percentiles are within each player's own tour. A side is highlighted only when the gap is larger than the margin on the difference.

Serve plan

The share of points the server wins when a first serve lands in that direction (hover a rate for its 90% interval; ± is the 90% margin). "Matchup" combines the server's rate with how this returner handles that serve. "Optimal" is the mix that wins most against this returner once they start reading a habit, at the response measured across the tour, and only within the range servers' habits actually vary. The gain over the current mix is how exploitable that mix is.

Simona Halep serving

Deuce court

1st serveNowSimona winsv SaraMatchupOptimal
Wide35%65%60%59.2%±8.034%
Body24%48%66%57.0%±9.99% ▼
T42%64%64%59.6%±8.357% ▲

Optimal v Sara Errani: +0.2±1.1 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving T every time would read +0.8 per 100 first serves in before the returner adjusts.

Ad court

1st serveNowSimona winsv SaraMatchupOptimal
Wide33%66%58%58.0%±9.218% ▼
Body27%59%54%56.7%±9.627%
T40%65%69%69.8%±7.455% ▲

Optimal v Sara Errani: +1.3±1.0 per 100 first serves (faults included) over the current mix. Serving T every time would read +7.4 per 100 first serves in before the returner adjusts.

Sara Errani serving

Deuce court

1st serveNowSara winsv SimonaMatchupOptimal
Wide35%54%64%51.7%±8.545% ▲
Body45%50%56%47.8%±8.530% ▼
T20%53%65%50.4%±9.225% ▲

Optimal v Simona Halep: +0.4±0.9 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving wide every time would read +2.0 per 100 first serves in before the returner adjusts.

Ad court

1st serveNowSara winsv SimonaMatchupOptimal
Wide37%54%61%48.9%±9.144% ▲
Body46%53%51%48.2%±9.131% ▼
T17%53%64%52.7%±9.925% ▲

Optimal v Simona Halep: +0.2±0.9 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving T every time would read +3.5 per 100 first serves in before the returner adjusts.

Return plan

Value of each return, in points per 100 returns against an average return of the same serve (direction, court, surface): the tour's result with that return, the returner's own edge with it, and what this server gives up when it comes back to that side. Returns with no charted direction are left out, so values compare with each other rather than with zero. Depth isn't a choice here: missed returns have no depth. Serve quality isn't charted, so a block through the middle partly reflects the serve that forced it.

Simona Halep returning

1st serve to the forehand

ReturnNowTourOwnv SaraValue
FH through the middle54%+4.2−0.3+0.5+4.3±2.7
FH down the line22%+1.5−0.9+6.0+6.6±4.3
FH crosscourt21%+5.3+2.5+5.9+13.7±4.0
FH slice through the middle2%−6.7+0.2+0.1−6.4±1.6

Lean FH crosscourt: +7.2±3.6 per 100 returns v the current mix (243 returns charted)

1st serve to the backhand

ReturnNowTourOwnv SaraValue
BH through the middle48%+6.0+0.5+1.7+8.2±2.5
BH crosscourt23%+7.7±0.0+4.0+11.7±3.1
BH down the line16%+2.2+2.0+6.9+11.1±4.4
BH slice through the middle8%−6.2−2.3+0.7−7.8±1.9
BH slice down the line4%−12.5−1.7±0.0−14.1±1.7

Lean BH crosscourt: +4.7±2.8 per 100 returns v the current mix (200 returns charted)

2nd serve to the forehand

ReturnNowTourOwnv SaraValue
FH through the middle43%−3.2+0.9−0.9−3.1±3.1
FH down the line36%−0.6+0.5+7.1+7.0±5.1
FH crosscourt21%+0.5−0.1+3.9+4.3±4.1

Lean FH down the line: +4.9±3.6 per 100 returns v the current mix (77 returns charted)

2nd serve to the backhand

ReturnNowTourOwnv SaraValue
BH crosscourt40%+1.5+0.3+0.3+2.1±3.6
BH through the middle38%−2.6±0.0−0.5−3.1±2.7
BH down the line14%−0.5+2.8+3.4+5.6±4.7
FH through the middle8%−2.7−0.3−0.9−3.9±2.3

Lean BH crosscourt: +2.0±2.5 per 100 returns v the current mix (87 returns charted, inside the 90% margin)

Sara Errani returning

1st serve to the forehand

ReturnNowTourOwnv SimonaValue
FH through the middle42%+4.2+2.7+1.4+8.2±2.8
FH down the line23%+1.5+4.7+0.1+6.4±4.6
FH crosscourt16%+5.3+0.6−0.2+5.7±4.4
FH slice through the middle13%−6.7+0.5−0.8−7.0±2.3
FH slice down the line6%−10.5−0.1±0.0−10.6±2.2

Lean FH through the middle: +3.9±2.1 per 100 returns v the current mix (394 returns charted)

1st serve to the backhand

ReturnNowTourOwnv SimonaValue
BH through the middle37%+6.0+1.9+0.8+8.8±2.6
BH crosscourt34%+7.7+1.5−1.2+8.1±3.5
BH slice through the middle13%−6.2+1.7−1.7−6.2±2.6
BH slice crosscourt7%−4.2−0.1−0.9−5.2±2.8
BH slice down the line5%−12.5+0.5+0.1−11.9±3.0

Lean BH through the middle: +4.4±2.1 per 100 returns v the current mix (315 returns charted)

2nd serve to the forehand

ReturnNowTourOwnv SimonaValue
FH through the middle45%−3.2+2.0−1.1−2.3±3.1
FH crosscourt30%+0.5+0.3+0.9+1.8±4.4
FH down the line26%−0.6+0.9+1.7+2.1±5.1

Lean FH down the line: +2.1±4.2 per 100 returns v the current mix (94 returns charted, inside the 90% margin)

2nd serve to the backhand

ReturnNowTourOwnv SimonaValue
BH crosscourt55%+1.5+1.4−0.9+1.9±3.5
BH through the middle29%−2.6+0.5−1.4−3.5±2.8
FH inside-out8%+1.4+0.6+1.7+3.7±3.9
FH through the middle4%−2.7+0.3−1.1−3.5±2.2
BH down the line3%−0.5−0.6+2.3+1.2±4.2

Lean BH crosscourt: +1.7±1.8 per 100 returns v the current mix (146 returns charted, inside the 90% margin)

Rally plan

Edge, in points per 100 shots: the hitter's skill with the shot (own) plus how much the receiver usually gives up against it (theirs), both measured against the tour average on grass. Each player's grass record is shrunk toward their all-surface one, so a thin sample on it moves the numbers only a little.

Simona Halep

Favour

ShotEdgeOwnTheirs
FH to their forehand · return+10.4±3.9+3.8+6.6
FH to their backhand · return+10.2±4.8−0.4+10.6
BH to their forehand · return+9.3±4.3+1.6+7.7
FH to the middle · return+5.6±3.7+2.0+3.6
BH to their forehand · rally+5.3±5.2−0.2+5.6
FH to their forehand · serve +1+5.3±3.7+1.6+3.7

Avoid

ShotEdgeOwnTheirs
BH to the middle · return +1−1.6±2.3−0.6−0.9
FH to the middle · serve +1+0.1±2.6+1.4−1.3
FH to their backhand · serve +1+0.2±3.6−1.8+2.0
BH to their backhand · serve +1+0.3±3.9−0.2+0.5
FH to their backhand · rally+0.8±4.9−0.7+1.5

Sara Errani

Favour

ShotEdgeOwnTheirs
FH to their forehand · return +1+5.7±3.8+4.1+1.6
FH to their backhand · rally+5.7±3.9+2.1+3.6
BH to their backhand · serve +1+5.1±3.9+4.8+0.3
BH slice to the middle · rally+4.9±2.9+1.5+3.3
BH to their backhand · return +1+4.6±3.1+3.2+1.4
BH to their forehand · rally+4.5±4.8+2.3+2.2

Avoid

ShotEdgeOwnTheirs
FH to their backhand · return +1−1.3±4.0+0.4−1.7
FH to their forehand · rally−0.9±4.2+0.9−1.8
BH slice to their backhand · rally−0.5±3.6−0.3−0.2
BH to their forehand · serve +1+0.3±4.9+0.4−0.2
FH to the middle · return +1+1.6±2.7+1.7−0.1

Against Sara Errani-like opponents

Simona Halep vMatchesServe pts wonReturn pts won
All charted opponents–55.4%46.0%
Players most similar to Sara Errani1 63.0%61.7%

Similar by tactical fingerprint: Tamara Zidansek, Viktorija Golubic, Daria Kasatkina, Maja Chwalinska, Sara Sorribes Tormo, Lesia Tsurenko, Alize Cornet, Kateryna Baindl, Madison Brengle, Tereza Martincova. When two players have rarely met, their records against these lookalikes fill the gap.