{"id":1844,"date":"2015-09-17T11:29:20","date_gmt":"2015-09-17T11:29:20","guid":{"rendered":"http:\/\/www.tennisabstract.com\/blog\/?p=1844"},"modified":"2015-09-17T11:29:20","modified_gmt":"2015-09-17T11:29:20","slug":"the-pivotal-point-of-15-30","status":"publish","type":"post","link":"https:\/\/www.tennisabstract.com\/blog\/2015\/09\/17\/the-pivotal-point-of-15-30\/","title":{"rendered":"The Pivotal Point of 15-30"},"content":{"rendered":"<p>According to nearly every tennis commentator I&#8217;ve ever heard, 15-30 is a crucial point, especially in men&#8217;s tennis, where breaks of serve are particularly rare. One reasonable explanation I&#8217;ve heard is that, from 15-30, if the server loses either of the next two points, he&#8217;ll face break point.<\/p>\n<p>Another way of looking at it is <a href=\"https:\/\/github.com\/JeffSackmann\/tennis_misc\/blob\/master\/tennisGameProbability.py\">with a theoretical model<\/a>. A player who wins 65% of service points (roughly average on the ATP tour) has a 62% chance of winning the game from 15-30. If he wins the next point, the probability rises to 78% at 30-all, but if he loses the next point, he will only have a 33% chance of saving the game from 15-40.<\/p>\n<p>Either way, 15-30 points have a lot riding on them. In line with <a href=\"http:\/\/www.tennisabstract.com\/blog\/2015\/09\/15\/how-important-is-the-first-point-of-each-game\/\">my analysis of the first point of each game<\/a> earlier this week, let&#8217;s take a closer look at 15-30 points&#8211;the odds of getting there, the outcome of the next point, and the chances of digging out a hold, along with\u00a0a look at which\u00a0players are particularly good or bad in these situations.<\/p>\n<p><b>Reaching 15-30<\/b><\/p>\n<p>In general, 15-30 points come up about once every four games, and no more or less often than we&#8217;d expect. In other words, games\u00a0aren&#8217;t particularly likely or unlikely to reach\u00a0that score.<\/p>\n<p>On the other hand, some particular\u00a0players are quite a bit more or less likely. \u00a0Oddly enough, big servers show up at both extremes. <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=JohnIsner\">John Isner<\/a> is the player who&#8211;relative to expectations&#8211;ends up serving at 15-30 the most often: 13% more than he should. Given the very high rate at which he wins service points, he should get to 15-30 in only 17% of service games, but he actually reaches 15-30 in 19% of service games.<\/p>\n<p>The list of players who serve at 15-30 more often than they should is a very mixed crew. I&#8217;ve extended this list to the top 13 in order to include another player in Isner&#8217;s category:<\/p>\n<pre>Player                 Games  ExpW  ActW  Ratio  \nJohn Isner             3166    537   608   1.13  \nJoao Sousa             1390    384   432   1.12  \nJanko Tipsarevic       1984    444   486   1.09  \nTommy Haas             1645    368   401   1.09  \nLleyton Hewitt         1442    391   425   1.09  \nTomas Berdych          3947    824   894   1.08  \nVasek Pospisil         1541    361   390   1.08  \nRafael Nadal           3209    661   713   1.08  \nPablo Andujar          1922    563   605   1.08  \nPhilipp Kohlschreiber  2948    652   698   1.07  \nGael Monfils           2319    547   585   1.07  \nLukasz Kubot           1360    381   405   1.06  \nIvo Karlovic           1941    299   318   1.06<\/pre>\n<p>(In all of these tables, &#8220;Games&#8221; is the number of service games for that player in the dataset, minimum 1,000 service games. &#8220;ExpW&#8221; is the expected number of occurences as predicted by the model, &#8220;ActW&#8221; is the actual number of times it happened, and &#8220;Ratio&#8221; is the ratio of actual occurences to expected occurences.)<\/p>\n<p>While getting to 15-30 this often is a bit of a disadvantage, it&#8217;s one that many of these players are able to erase. Isner, for example, not only remains the favorite at 15-30&#8211;his average rate of service points won, 72%, implies that he&#8217;ll win 75% of games from 15-30&#8211;but from this score, he wins 11% more often\u00a0than he should.<\/p>\n<p>To varying extents, that&#8217;s true of every player on the list. <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=JoaoSousa\">Joao Sousa<\/a> doesn&#8217;t entirely make up for the frequency with which he ends up at 15-30, but he does win 4% more often from 15-30 than he should. <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=RafaelNadal\">Rafael Nadal<\/a>, <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=TomasBerdych\">Tomas Berdych<\/a>, and <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=GaelMonfils\">Gael Monfils<\/a> all win between 6% and 8% more often from 15-30 than the theoretical model suggests that they would. In Nadal&#8217;s case, it&#8217;s almost certainly related to his skill in the ad court, particularly in saving break points.<\/p>\n<p>At the other extreme, we have players we might term &#8220;strong starters&#8221; who avoid 15-30 more often than we&#8217;d expect. Again, it&#8217;s a bit of a mixed bag:<\/p>\n<pre>Player                 Games  ExpW  ActW  Ratio  \nDustin Brown           1013    249   216   0.87  \nVictor Hanescu         1181    308   274   0.89  \nMilos Raonic           3050    514   462   0.90  \nDudi Sela              1066    297   270   0.91  \nRichard Gasquet        2897    641   593   0.93  \nJuan Martin del Potro  2259    469   438   0.93  \nErnests Gulbis         2308    534   500   0.94  \nKevin Anderson         2946    610   571   0.94  \nNikolay Davydenko      1488    412   388   0.94  \nNicolas Mahut          1344    314   297   0.94<\/pre>\n<p>With some exceptions, many of the players\u00a0on this list are thought to be weak in the clutch. (The Dutch pair of <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=RobinHaase\">Robin Haase<\/a> and <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=IgorSijsling\">Igor Sijsling<\/a> are 12th and 13th.) This makes sense, as the pressure is typically lowest early in games. A player who wins points more often at, say, 15-0 than at 40-30 isn&#8217;t going to get much of a reputation for coming through when it counts.<\/p>\n<p>The same analysis for returners isn&#8217;t as interesting. <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=JuanMartinDelPotro\">Juan Martin del Potro<\/a> comes up again as one of the players least likely to get to 15-30, and Isner&#8211;to my surprise&#8211;is one of the most likely. There&#8217;s not much of a pattern among the best returners: <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=NovakDjokovic\">Novak Djokovic<\/a> gets to 15-30 2% less often than expected; Nadal 1% less often, <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=AndyMurray\">Andy Murray<\/a> exactly as often as expected, and <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=DavidFerrer\">David Ferrer<\/a> 3% more often.<\/p>\n<p>Before moving on, one final note about reaching 15-30. Returners are much less likely to apply enough pressure to reach 15-30 when they are already in a strong position\u00a0to win the set. At scores such as 0-4, 0-5, and 1-5, the score reaches 15-30 10% less often than usual. At the other extreme, two of the games in which a 15-30 score is most common are 5-6 and 6-5, when the score reaches 15-30 about 8% more often than usual.<\/p>\n<p><strong>The high-leverage next point<\/strong><\/p>\n<p>As we&#8217;ve seen, there&#8217;s a huge difference between winning and losing a 15-30 point. In the 290,000 matches I analyzed for this post, neither the server or returner has an advantage at 15-30. However, some players do perform better than others.<\/p>\n<p>Measured by their success rate serving at 15-30 relative to their typical rate of service points won, here is the top 11, a list unsurprisingly dotted with lefties:<\/p>\n<pre>Player             Games  ExpW  ActW  Ratio  \nDonald Young       1298    204   229   1.12  \nRobin Haase        2134    322   347   1.08  \nSteve Johnson      1194    181   195   1.08  \nBenoit Paire       1848    313   336   1.08  \nFernando Verdasco  2571    395   423   1.07  \nThomaz Bellucci    1906    300   321   1.07  \nJohn Isner         3166    421   449   1.07  \nXavier Malisse     1125    175   186   1.06  \nVasek Pospisil     1541    243   258   1.06  \nRafael Nadal       3209    470   497   1.06  \nBernard Tomic      2124    328   347   1.06<\/pre>\n<p>There&#8217;s Isner again, making up for reaching 15-30 more often than he should.<\/p>\n<p>And here are the players who win 15-30 points less often than other service points:<\/p>\n<pre>Player                  Games  ExpW  ActW  Ratio  \nCarlos Berlocq          1867    303   273   0.90  \nAlbert Montanes         1183    191   173   0.91  \nKevin Anderson          2946    377   342   0.91  \nGuillermo Garcia-Lopez  2356    397   370   0.93  \nRoberto Bautista-Agut   1716    264   247   0.93  \nJuan Monaco             2326    360   338   0.94  \nMatthew Ebden           1088    186   176   0.94  \nGrigor Dimitrov         2647    360   341   0.95  \nRichard Gasquet         2897    380   360   0.95  \nAndy Murray             3416    473   449   0.95<\/pre>\n<p>When we turn to <em>return<\/em> performance at 15-30, the extremes are less interesting. However, returning at this crucial score\u00a0is something that is at least weakly correlated with overall success: Eight of the current top ten (all but <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=RogerFederer\">Roger Federer<\/a> and <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=MilosRaonic\">Milos Raonic<\/a>) win more 15-30 points than expected. Djokovic wins 4% more than expected, while Nadal and Tomas Berdych win 3% more.<\/p>\n<p>Again, breaking down 15-30 performance by situation is instructive. When the server has a substantial advantage in the set&#8211;at scores such as 5-1, 4-0, 3-2, and 3-0&#8211;he is less likely to win the 15-30 point. But when the server is trailing by a large margin&#8211;0-3, 1-4, 0-4, etc.&#8211;he is more likely to win the 15-30 point. This is a bit of evidence, though peripheral, of the difficulty of closing out a set&#8211;a subject for another day.<\/p>\n<p><strong>Winning the game from 15-30<\/strong><\/p>\n<p>For the server, getting to 15-30 isn&#8217;t a good idea. But compared to our theoretical model, it isn&#8217;t quite as bad as it seems. From 15-30, the server wins 2% more often than the model predicts. While it&#8217;s not a large effect, it is a persistent one.<\/p>\n<p>Here are the players who play better than usual from 15-30, winning games much more often than the model predicts they would:<\/p>\n<pre>Player             Games  ExpW  ActW  Ratio  \nNikolay Davydenko  1488    194   228   1.17  \nSteve Johnson      1194    166   190   1.14  \nDonald Young       1298    163   185   1.13  \nJohn Isner         3166    423   470   1.11  \nNicolas Mahut      1344    172   188   1.09  \nBenoit Paire       1848    266   288   1.08  \nLukas Lacko        1162    164   177   1.08  \nRafael Nadal       3209    450   484   1.08  \nMartin Klizan      1534    201   216   1.08  \nFeliciano Lopez    2598    341   367   1.07  \nTomas Berdych      3947    556   597   1.07<\/pre>\n<p>Naturally, this list has much in common with that of the players who excel on the 15-30 point itself, including many lefties. The big surprise is <a href=\"http:\/\/www.tennisabstract.com\/cgi-bin\/player.cgi?p=NikolayDavydenko\">Nikolay Davydenko<\/a>, a player who many regarded as weak in the clutch, and who showed up on one of the first lists among players with questionable reputations in pressure situations. Yet Davydenko&#8211;at least at the end of his career&#8211;was very effective at times like these.<\/p>\n<p>Another note on Nadal: He is the only player on this list who is also near the top among men who\u00a0overperform from 15-30 on return. Rafa exceeds expectations in that category by 7%, as well, better than any other player in the last few years.<\/p>\n<p>And finally, here are the players who underperform from 15-30 on serve:<\/p>\n<pre>Player               Games  ExpW  ActW  Ratio  \nDustin Brown         1013    122   111   0.91  \nTommy Robredo        2140    289   270   0.93  \nAlexandr Dolgopolov  2379    306   288   0.94  \nFederico Delbonis    1110    157   148   0.94  \nJuan Monaco          2326    304   289   0.95  \nSimone Bolelli       1015    132   126   0.96  \nPaul-Henri Mathieu   1083    155   148   0.96  \nGilles Muller        1332    179   172   0.96  \nCarlos Berlocq       1867    256   246   0.96  \nGrigor Dimitrov      2647    333   320   0.96  \nRichard Gasquet      2897    352   339   0.96<\/pre>\n<p><strong>Tentative conclusions<\/strong><\/p>\n<p>This is one subject on which the conventional wisdom and statistical analysis agree, at least to a certain extent. 15-30 is a very important point, though in context, it&#8217;s no more important than some of the points that follow.<\/p>\n<p>These numbers show that some players are better than others at certain stages within each game. In some cases, the strengths balance out with other weaknesses; in others, the stats may expose pressure situations where a\u00a0player falters.<\/p>\n<p>While many of the extremes I&#8217;ve listed here are significant, it&#8217;s important to keep them in context. For the average player, games reach 15-30 about one-quarter of the time, so performing 10% better or worse in these situations affects only one in <em>forty<\/em>\u00a0games.<\/p>\n<p>Over the course of a career, it adds up, but we&#8217;re rarely going to be able to spot these trends during a single match, or even within a tournament. While outperforming expectations on 15-30 points (or any other small subset) is helpful, it&#8217;s rarely something the best players rely on. If you play as well as Djokovic does, you don&#8217;t need to play even better in clutch situations. Simply meeting expectations is enough.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>According to nearly every tennis commentator I&#8217;ve ever heard, 15-30 is a crucial point, especially in men&#8217;s tennis, where breaks of serve are particularly rare. One reasonable explanation I&#8217;ve heard is that, from 15-30, if the server loses either of the next two points, he&#8217;ll face break point. Another way of looking at it is &hellip; <a href=\"https:\/\/www.tennisabstract.com\/blog\/2015\/09\/17\/the-pivotal-point-of-15-30\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">The Pivotal Point of 15-30<\/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":[18,96,123],"tags":[],"class_list":["post-1844","post","type-post","status-publish","format-standard","hentry","category-clutch","category-research","category-win-probability"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/posts\/1844","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=1844"}],"version-history":[{"count":0,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/posts\/1844\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/media?parent=1844"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/categories?post=1844"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/tags?post=1844"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}