RallyIQ

Game plan

Sloane Stephens v Iga Swiatek

Every number combines what Sloane Stephens does well with what Iga Swiatek allows, each measured against the tour average and shrunk toward it when the sample is thin. Flip perspective

Forecast

Sloane Stephens wins, best of 3 9%90%: 2%–25% · best of 5: 5%
Serve points won 51.5% / 61.5% Sloane / Iga · tour 56.3%
Strengths only, no similarity priors 11%serve 51.4% / 60.8%

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 At least one of them is no longer active or has too little charted in the last three seasons, so both are compared on their careers.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 Sloane Stephens's record against Iga Swiatek's tactical lookalikes and in their charted head-to-heads (lookalikes: +2.4 on serve, −7.0 on return vs expectation (228 points); head-to-head: −1.4 on serve, −2.1 on return vs expectation (236 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

CareerSloaneIga
Direction choice−0.12 ±0.11
better than 32%
+0.17 ±0.03
better than 82%
Shot selection−0.16 ±0.14
better than 31%
+0.32 ±0.04
better than 81%
Execution−0.13 ±0.58
better than 56%
+0.91 ±0.19
better than 89%
Points left on the table2.62 ±0.13
lower than 48%
2.13 ±0.04
lower than 96%

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: Sloane Stephens −1.27, Iga Swiatek +0.09. 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.

Sloane Stephens serving

Deuce court

1st serveNowSloane winsv IgaMatchupOptimal
Wide50%66%60%60.2%±4.365% ▲
Body30%56%51%49.8%±5.315% ▼
T20%63%61%55.7%±6.220%

Optimal v Iga Swiatek: +0.7±0.7 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving wide every time would read +4.0 per 100 first serves in before the returner adjusts.

Ad court

1st serveNowSloane winsv IgaMatchupOptimal
Wide32%60%62%55.6%±5.231% ▼
Body13%53%51%47.3%±7.50% ▼
T55%61%59%56.1%±4.469% ▲

Optimal v Iga Swiatek: +0.7±0.7 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving T every time would read +1.3 per 100 first serves in before the returner adjusts.

Iga Swiatek serving

Deuce court

1st serveNowIga winsv SloaneMatchupOptimal
Wide40%69%66%69.4%±4.540%
Body28%64%58%64.2%±5.312% ▼
T32%73%71%75.0%±4.348% ▲

Optimal v Sloane Stephens: +0.8±0.8 per 100 first serves (faults included) over the current mix. Serving T every time would read +5.2 per 100 first serves in before the returner adjusts.

Ad court

1st serveNowIga winsv SloaneMatchupOptimal
Wide38%72%64%70.1%±4.337%
Body29%63%59%65.3%±6.414% ▼
T33%68%67%70.8%±4.749% ▲

Optimal v Sloane Stephens: +0.5±0.8 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving T every time would read +1.9 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.

Sloane Stephens returning

1st serve to the forehand

ReturnNowTourOwnv IgaValue
FH through the middle37%+4.2+2.0−1.2+5.0±2.0
FH slice through the middle20%−6.7−0.4−0.9−8.0±2.2
FH crosscourt14%+5.3−1.5−0.6+3.2±3.4
FH down the line13%+1.5−0.6−3.6−2.6±3.7
FH slice crosscourt12%−6.6+0.3−0.3−6.7±2.6

Lean FH through the middle: +6.1±1.5 per 100 returns v the current mix (466 returns charted)

1st serve to the backhand

ReturnNowTourOwnv IgaValue
BH through the middle43%+6.0−0.1−1.3+4.6±1.8
BH crosscourt32%+7.7+0.3−1.2+6.9±2.5
BH down the line10%+2.2−3.1−2.7−3.6±3.7
BH slice through the middle8%−6.2−2.7−0.8−9.7±2.4
BH slice crosscourt4%−4.2−1.3−5.0−10.5±2.8

Lean BH crosscourt: +4.8±1.9 per 100 returns v the current mix (509 returns charted)

2nd serve to the forehand

ReturnNowTourOwnv IgaValue
FH through the middle58%−3.2+0.2−0.4−3.4±2.5
FH crosscourt26%+0.5−1.5−2.3−3.3±3.5
FH down the line10%−0.6−0.5−0.2−1.3±3.6
FH slice through the middle6%−15.2−0.8−1.0−17.0±2.0

Lean FH crosscourt: +0.6±3.0 per 100 returns v the current mix (88 returns charted, inside the 90% margin)

2nd serve to the backhand

ReturnNowTourOwnv IgaValue
BH through the middle45%−2.6−0.9±0.0−3.6±1.9
BH crosscourt41%+1.5−1.0−0.9−0.4±2.6
BH down the line6%−0.5−0.1−0.8−1.4±3.9
FH through the middle5%−2.7±0.0−0.4−3.1±1.8
FH inside-out3%+1.4+2.3−0.2+3.5±2.9

Lean BH crosscourt: +1.5±1.8 per 100 returns v the current mix (299 returns charted, inside the 90% margin)

Iga Swiatek returning

1st serve to the forehand

ReturnNowTourOwnv SloaneValue
FH through the middle51%+4.2+0.8+1.2+6.1±1.5
FH crosscourt25%+5.3+0.1+0.8+6.2±2.9
FH down the line15%+1.5−2.7+0.6−0.5±3.4
FH slice through the middle6%−6.7−0.5−1.7−9.0±2.3
FH slice crosscourt3%−6.6−3.5−1.3−11.3±2.6

Lean FH crosscourt: +2.5±2.3 per 100 returns v the current mix (3485 returns charted)

1st serve to the backhand

ReturnNowTourOwnv SloaneValue
BH through the middle50%+6.0+0.4−0.4+6.0±1.6
BH crosscourt32%+7.7+0.7+2.2+10.6±2.4
BH down the line10%+2.2+2.9−1.0+4.1±3.8
BH slice through the middle4%−6.2−0.6−0.4−7.2±2.4
BH slice crosscourt3%−4.2−3.2±0.0−7.4±2.6

Lean BH crosscourt: +4.6±1.8 per 100 returns v the current mix (3016 returns charted)

2nd serve to the forehand

ReturnNowTourOwnv SloaneValue
FH through the middle41%−3.2+1.2−0.2−2.2±2.5
FH crosscourt40%+0.5−0.6+1.6+1.6±3.7
FH down the line17%−0.6−1.4−0.9−2.8±4.9
FH slice through the middle1%−15.2±0.0±0.0−15.2±1.6
FH slice crosscourt1%−14.9−0.1±0.0−15.0±1.5

Lean FH crosscourt: +2.7±2.6 per 100 returns v the current mix (1030 returns charted)

2nd serve to the backhand

ReturnNowTourOwnv SloaneValue
BH crosscourt47%+1.5+1.2−0.5+2.3±2.4
BH through the middle33%−2.6+0.2−2.3−4.7±2.0
BH down the line19%−0.5+4.4−0.4+3.6±4.5
FH inside-in1%+0.7−3.3+1.6−0.9±4.2
FH through the middle0%−2.7−1.1−0.2−4.0±2.2

Lean BH down the line: +3.5±3.8 per 100 returns v the current mix (1717 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.

Sloane Stephens

Favour

ShotEdgeOwnTheirs
BH to their forehand · return +1+1.2±3.6+2.3−1.1
FH slice to their forehand · return+0.3±2.7+0.3±0.0
FH to their forehand · rally+0.1±1.5+1.3−1.2
BH to their backhand · serve +1±0.0±2.2+0.6−0.6
FH to the middle · return +1−0.1±1.9+0.1−0.2
FH to the middle · serve +1−0.1±1.6−0.1−0.1

Avoid

ShotEdgeOwnTheirs
FH to their forehand · return−4.3±3.0−3.4−0.9
BH to their forehand · return−4.2±3.3−2.3−1.9
FH to their forehand · return +1−3.5±2.5−2.2−1.2
BH to the middle · return +1−3.2±1.6−2.8−0.4
BH slice to the middle · rally−3.0±1.8−2.6−0.4

Iga Swiatek

Favour

ShotEdgeOwnTheirs
FH to the middle · return+3.1±1.4+1.0+2.1
BH to their forehand · serve +1+2.8±3.4+3.5−0.6
BH to their forehand · return+2.2±3.0+2.9−0.7
BH to their backhand · return+2.0±1.9+1.1+1.0
FH to their forehand · serve +1+1.9±2.3+2.1−0.2
BH to their forehand · rally+1.4±2.7+3.0−1.5

Avoid

ShotEdgeOwnTheirs
BH slice to their backhand · rally−3.1±2.7−3.4+0.3
BH to the middle · return +1−3.1±1.7−0.4−2.6
FH to the middle · rally−2.1±1.3−1.1−1.1
BH slice to the middle · rally−2.1±2.2−1.1−1.0
FH to their forehand · rally−1.5±1.5+1.1−2.6

Against Iga Swiatek-like opponents

Sloane Stephens vMatchesServe pts wonReturn pts won
All charted opponents–56.4%42.8%
Players most similar to Iga Swiatek1 58.2%36.4%
Iga Swiatek (charted head-to-head)2 50.0%36.8%

Similar by tactical fingerprint: Anastasia Potapova, Karolina Pliskova, Anna Kalinskaya, Anna Blinkova, Ekaterina Alexandrova, Sorana Cirstea, Shuai Zhang, Varvara Gracheva, Anett Kontaveit, Eugenie Bouchard. When two players have rarely met, their records against these lookalikes fill the gap.

Charted head-to-head