In professional tennis, it’s a given that the server has an advantage. \u00a0The size of that advantage depends on the abilities of the two players and the surface, but especially in men’s tennis, it’s a sizable edge. \u00a0On average, a server in an ATP match starts a point with a roughly 65% chance of winning.<\/p>\n
But how long does it last? \u00a0It seems that, at some stage in the rally, the server’s advantage has disappeared. \u00a0Four or five strokes in, the server may still be benefiting from an off-balance return. \u00a0But by ten strokes, one would assume that the rally is neutral–that the advantage conferred by serving has evaporated.<\/p>\n
As usual with tennis analysis, one question begets several more. \u00a0Does the server’s advantage last longer on faster surfaces? \u00a0Do women settle into “neutral” rallies sooner than men do? \u00a0Do dominating players, like this year’s edition of Novak Djokovic, take away the server’s advantage faster than the average player?<\/p>\n
Using the rally counts provided by Pointstream at the last three majors, we can start to answer these questions.<\/p>\n
Neutralizing the serve<\/strong><\/p>\n The first step is to take all the matches we have rally-count data for, and average them out. \u00a0Then, for each point length, we calculate the odds that the server wins a point of at least<\/em>\u00a0that length. \u00a0So, for instance, we look at all points of five shots or more, and figure out how many of those the server wins.<\/p>\n Each one of these numbers is biased, because a rally of\u00a0exactly<\/em>\u00a0five-strokes is, by definition, won by the server. \u00a0The server either hits a winner on his third shot (the fifth overall), or the returner makes an error attempting to hit his own third shot (the sixth overall). \u00a0Thus, if we look at all points of at least<\/em>\u00a0five strokes, the exactly <\/em>five-stroke rallies virtually guarantee that the server will have the advantage.<\/p>\n However, the same reasoning shows us that a six-stroke<\/em>\u00a0rally will be biased in favor of the returner. \u00a0When we do the math for at-least-five, at-least-six, at-least-seven, and so on, we’ll see a yo-yo effect. \u00a0When the biases have equal effect, that means the serve is neutralized.<\/p>\n Here are the results for the approximately 150 grand slam matches with Pointstream data so far this year:<\/p>\n In the table, “Win%” refers to the server’s chance of winning the point. \u00a0The biases even out somewhere between the 4th and 8th shot<\/strong>, meaning that in that zone, the server’s advantage is neutralized.<\/p>\n While the server retains the advantage at least until the fourth shot, it is interesting to see how quickly it decays. \u00a0Dropping from 66% upon making a serve to 56% once the advantage is neutralized, it loses more than half the difference between the first and third shots. \u00a0Thus, the returner doesn’t negate the server’s advantage simply by getting the ball back in play, but he does take a large step toward doing so.<\/p>\n Does surface matter?<\/strong><\/p>\n As usual, it sure does. \u00a0The numbers for the Australian and French Opens are similar, and since they make up 2\/3 of the data set, they are close to the aggregate numbers shown above. \u00a0But Wimbledon, as is so often the case, seems to play by a different set of rules:<\/p>\n The biases don’t balance out until the very bottom–at 14 or more shots! \u00a0That’s only about 3% of points. \u00a0I’m not sure how to explain this, except perhaps psychologically, that on grass (considered the best surface for servers), players are less successful in return games simply because that’s what they expect to happen. \u00a0Regardless of surface, I can’t understand why else the server’s advantage would persist into double-digit shot counts.<\/p>\n What about the ladies?<\/strong><\/p>\n WTA players (on average) start each service point with a smaller advantage than their male counterparts, and as it turns out, that advantage evaporates more quickly.<\/p>\n We saw a moment ago that, by putting the return in play, an ATP returner gives himself a 50% chance of winning the point–at least until his opponent hits another shot. \u00a0Women, however, knock the server’s winning percentage down to 47% by making the return.<\/p>\n The returner clearly neutralizes the point by the fourth stroke overall, and–here’s the good part–takes over a slight advantage herself by her third shot, the sixth stroke overall. \u00a0By making that sixth shot, the returner has a 57% chance of winning the point, while the server will never reach 57% again. \u00a0The advantage is only a percentage or two, but from the sixth stroke on, the returner has the edge.<\/p>\n Finally, presenting Novak Djokovic<\/strong><\/p>\n Pointstream has tracked 17 of Djokovic’s slam matches this year, giving us a good set of data to work with. \u00a0When a man is having a season like this one<\/a>–in large part because of his return game<\/a>–it’s fascinating to see how comprehensively he is outplaying his opponents.<\/p>\n In the same terms as the tables above, here are Djokovic’s serve and return points across those 17 matches. \u00a0The return points are shown with the server’s winning percentages:<\/p>\n After seeing the averages above, you might reasonably conclude that these numbers are out of this world. \u00a0Even with the bias of 4-, 6-, and 8-stroke rallies, as discussed above, Djokovic still maintains an edge. \u00a0For everyone else, once fifth or sixth shot is struck, the point is a 50\/50 proposition. \u00a0For Novak, it’s at least 60\/40 in his favor.<\/p>\n The amazing stats are on his return. \u00a0When he gets his return back in play, he’s more than likely to win the point. \u00a0<\/strong>That may not surprise anyone who has watched Djokovic play this year, but consider how remarkable that is in the context of modern men’s tennis. \u00a0By the 8th stroke or so, he’s back to the 60\/40 odds of the service points that turn into longer rallies.<\/p>\n Thanks to Carl Bialik for suggesting this topic.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":" In professional tennis, it’s a given that the server has an advantage. \u00a0The size of that advantage depends on the abilities of the two players and the surface, but especially in men’s tennis, it’s a sizable edge. \u00a0On average, a server in an ATP match starts a point with a roughly 65% chance of winning. … Continue reading How Long Does the Server’s Advantage Last?<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[96],"tags":[],"class_list":["post-472","post","type-post","status-publish","format-standard","hentry","category-research"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/posts\/472","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/comments?post=472"}],"version-history":[{"count":0,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/posts\/472\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/media?parent=472"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/categories?post=472"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/tags?post=472"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}At least\u2026 Win% Notes \n0 63% before point begins \n1 66% if serve goes in \n2 50% if serve is returned \n3 60% if server makes second shot \n4 46% if returner makes second shot \n5 58% \n6 45% \n7 57% \n8 44% \n9 56% \n10 44% \n11 56% \n12 43% \n13 56% \n14 43% \n15 56%<\/pre>\n
At least\u2026 Wimby Austr French \n0 66% 62% 62% \n1 68% 64% 67% \n2 52% 50% 48% \n3 62% 59% 58% \n4 48% 46% 45% \n5 61% 57% 57% \n6 47% 44% 44% \n7 61% 55% 56% \n8 47% 44% 44% \n9 59% 55% 54% \n10 47% 43% 43% \n11 60% 54% 55% \n12 46% 43% 43% \n13 59% 55% 55% \n14 43% 45% 42% \n15 56% 54% 56%<\/pre>\n
At least\u2026 ND Sv ND Ret \n0 70% 57% \n1 72% 60% \n2 59% 42% \n3 68% 50% \n4 56% 39% \n5 68% 49% \n6 57% 38% \n7 68% 47% \n8 58% 38% \n9 68% 45% \n10 55% 34% \n11 65% 44% \n12 55% 33% \n13 66% 38% \n14 52% 29% \n15 65% 40%<\/pre>\n