RallyIQ

Game plan

Sara Errani v Diane Parry

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

Forecast

Sara Errani wins, best of 3 29%90%: 9%–59% · best of 5: 24%
Serve points won 54.0% / 58.3% Sara / Diane · tour 56.4%
Strengths only, no similarity priors 27%serve 53.7% / 58.3%

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 At least one of them is no longer active or has too little charted in the last three seasons, so both are compared on their careers.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 Sara Errani's record against Diane Parry's tactical lookalikes and in their charted head-to-heads (lookalikes: +6.3 on serve, −0.1 on return vs expectation (184 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

CareerSaraDiane
Direction choice−0.23 ±0.11
better than 14%
−0.09 ±0.09
better than 38%
Shot selection−0.34 ±0.17
better than 19%
−1.27 ±0.44
better than 2%
Execution+1.67 ±0.48
better than 97%
−0.23 ±0.93
better than 47%
Points left on the table2.62 ±0.13
lower than 48%
3.19 ±0.22
lower than 5%

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.

Structural compatibility

Expected edge per 100 rally shots from style alone: Sara Errani +0.78, Diane Parry +0.80. Each player's shot mix weighted by their own skill with each shot and by how much the other gives up against it. This is why some rankings gaps don't hold in a given matchup.

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.

Sara Errani serving

Deuce court

1st serveNowSara winsv DianeMatchupOptimal
Wide35%54%74%63.7%±8.550% ▲
Body45%50%57%49.3%±8.930% ▼
T20%53%71%56.4%±9.420%

Optimal v Diane Parry: +0.9±1.1 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving wide every time would read +8.0 per 100 first serves in before the returner adjusts.

Ad court

1st serveNowSara winsv DianeMatchupOptimal
Wide37%54%72%61.4%±7.852% ▲
Body46%53%56%53.1%±9.831% ▼
T17%53%68%57.2%±10.717%

Optimal v Diane Parry: +0.7±1.1 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving wide every time would read +4.5 per 100 first serves in before the returner adjusts.

Diane Parry serving

Deuce court

1st serveNowDiane winsv SaraMatchupOptimal
Wide43%68%60%62.3%±7.743%
Body18%58%66%66.0%±9.63% ▼
T39%71%64%67.2%±8.554% ▲

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 +2.3 per 100 first serves in before the returner adjusts.

Ad court

1st serveNowDiane winsv SaraMatchupOptimal
Wide34%61%58%53.0%±8.925% ▼
Body15%57%54%54.4%±11.09% ▼
T51%63%69%67.9%±7.466% ▲

Optimal v Sara Errani: +0.9±0.9 per 100 first serves (faults included) over the current mix. Serving T every time would read +7.1 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.

Sara Errani returning

1st serve to the forehand

ReturnNowTourOwnv DianeValue
FH through the middle42%+4.2+2.7−2.0+4.8±2.8
FH down the line23%+1.5+4.7−3.4+2.8±4.6
FH crosscourt16%+5.3+0.6+3.1+9.0±4.4
FH slice through the middle13%−6.7+0.5+0.6−5.6±2.6
FH slice down the line6%−10.5−0.1+1.8−8.8±3.1

Lean FH crosscourt: +6.1±4.0 per 100 returns v the current mix (394 returns charted)

1st serve to the backhand

ReturnNowTourOwnv DianeValue
BH through the middle37%+6.0+1.9−0.1+7.8±2.7
BH crosscourt34%+7.7+1.5+1.8+11.0±3.5
BH slice through the middle13%−6.2+1.7−0.4−4.9±2.5
BH slice crosscourt7%−4.2−0.1+1.2−3.1±2.8
BH slice down the line5%−12.5+0.5+0.2−11.8±2.9

Lean BH crosscourt: +5.7±2.6 per 100 returns v the current mix (315 returns charted)

2nd serve to the forehand

ReturnNowTourOwnv DianeValue
FH through the middle45%−3.2+2.0−0.1−1.3±3.1
FH crosscourt30%+0.5+0.3+1.5+2.4±4.2
FH down the line26%−0.6+0.9+0.8+1.2±4.6

Lean FH crosscourt: +2.0±3.4 per 100 returns v the current mix (94 returns charted, inside the 90% margin)

2nd serve to the backhand

ReturnNowTourOwnv DianeValue
BH crosscourt55%+1.5+1.4−0.2+2.7±3.6
BH through the middle29%−2.6+0.5−1.4−3.5±2.7
FH inside-out8%+1.4+0.6+0.8+2.7±3.4
FH through the middle4%−2.7+0.3−0.1−2.5±2.2
BH down the line3%−0.5−0.6+0.1−1.0±4.2

Lean BH crosscourt: +2.2±1.8 per 100 returns v the current mix (146 returns charted)

Diane Parry returning

1st serve to the forehand

ReturnNowTourOwnv SaraValue
FH through the middle37%+4.2−1.3+0.5+3.4±2.8
FH down the line27%+1.5−0.1+6.0+7.4±4.3
FH slice through the middle21%−6.7+0.1+0.1−6.5±2.1
FH slice crosscourt6%−6.6+0.8±0.0−5.8±1.6
FH crosscourt5%+5.3−4.0+5.9+7.3±3.3

Lean FH down the line: +6.1±3.4 per 100 returns v the current mix (189 returns charted)

1st serve to the backhand

ReturnNowTourOwnv SaraValue
BH slice through the middle51%−6.2+0.3+0.7−5.2±1.9
BH slice crosscourt18%−4.2+2.2−0.4−2.4±2.7
BH through the middle14%+6.0−3.0+1.7+4.7±2.6
BH slice down the line8%−12.5+1.0±0.0−11.5±2.3
BH crosscourt6%+7.7−3.1+4.0+8.6±2.8

Lean BH crosscourt: +11.1±2.9 per 100 returns v the current mix (242 returns charted)

2nd serve to the forehand

ReturnNowTourOwnv SaraValue
FH down the line48%−0.6+0.5+7.1+7.0±5.1
FH through the middle39%−3.2−1.7−0.9−5.8±3.0
FH crosscourt13%+0.5+1.3+3.9+5.8±3.8

Lean FH down the line: +5.1±2.9 per 100 returns v the current mix (62 returns charted)

2nd serve to the backhand

ReturnNowTourOwnv SaraValue
BH slice through the middle22%−11.7+0.1±0.0−11.6±1.6
FH inside-out19%+1.4+0.4+7.1+8.8±4.1
BH through the middle18%−2.6+0.8−0.5−2.3±2.6
BH slice crosscourt15%−7.5−1.7+0.3−8.8±2.2
FH through the middle15%−2.7+1.5−0.9−2.0±2.5

Lean FH inside-out: +11.5±3.4 per 100 returns v the current mix (110 returns charted)

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 hard. Each player's hard record is shrunk toward their all-surface one, so a thin sample on it moves the numbers only a little.

Sara Errani

Favour

ShotEdgeOwnTheirs
BH to their forehand · rally+10.6±6.1+6.6+4.1
BH to their backhand · return+5.8±4.8+4.6+1.2
FH to the middle · return +1+5.7±4.0+2.5+3.2
BH to their backhand · return +1+5.1±4.8+4.2+0.8
FH to their forehand · return +1+4.7±5.5+6.1−1.3
FH to their forehand · serve +1+4.4±5.5+3.4+1.0

Avoid

ShotEdgeOwnTheirs
BH to their backhand · serve +1−4.3±4.7+2.7−7.0
FH to the middle · return−1.4±3.6+1.6−3.0
BH to their forehand · serve +1−1.2±7.2+1.2−2.4
FH to their backhand · serve +1−1.1±5.5+2.2−3.3
BH to the middle · return−1.1±3.2+2.0−3.1

Diane Parry

Favour

ShotEdgeOwnTheirs
FH to their backhand · return +1+6.6±5.9+3.9+2.7
FH to their backhand · return+5.9±5.5−0.9+6.7
FH to their backhand · serve +1+4.1±5.0+1.8+2.3
FH to their forehand · rally+2.8±3.4−1.0+3.8
BH to the middle · rally+2.7±3.0+0.5+2.1
FH to their forehand · serve +1+2.3±5.2−4.3+6.6

Avoid

ShotEdgeOwnTheirs
FH to their forehand · return +1−6.2±5.5−4.4−1.8
FH to the middle · serve +1−3.6±3.8−2.7−0.9
BH slice to their forehand · rally−3.1±5.4−3.6+0.5
FH to the middle · return−1.9±3.6−3.6+1.7
BH to their backhand · rally+1.2±4.1−2.4+3.5

Against Diane Parry-like opponents

Sara Errani vMatchesServe pts wonReturn pts won
All charted opponents–47.3%44.7%
Players most similar to Diane Parry1 60.4%44.1%

Similar by tactical fingerprint: Karolina Muchova, Caty Mcnally, Tamara Zidansek, Anna Bondar, Daria Saville, Samantha Stosur, Ashleigh Barty, Polona Hercog, Francesca Schiavone, Roberta Vinci. When two players have rarely met, their records against these lookalikes fill the gap.