The perception in tennis is that some players are always dark horses, guys who on any given day might play well above their ranking. Often, these players have “top ten talent” coupled with mental lapses–think Gael Monfils, Marcos Baghdatis, Thomaz Bellucci, Philipp Kohlschreiber. Their rankings sag because of brainless losses (Monfils to Lukasz Kubot at Wimbledon, Baghdatis to somebody every third week), but they occasionally flash their brilliance with a surprising result.
Put it together, and you have a dark horse. There’s a special sort of dark horse upon whom everyone seems to agree: the freakishly tall ace machine. Rob Koenig sounds sensible tweeting about Roger Federer‘s third round match against Ivo Karlovic: “Karlovic v Fed?? Even though Fed has a good record against him, he’s not a guy you wanna see on your side of the draw.” That’s the official line before just about every match Ivo or John Isner plays. The unstoppable serves make them capable of anything.
Or do they? A barrage of bombs starting almost ten feet in the air and bouncing over your head doesn’t sound like a fun day on the court, but does it translate into more losses for top players?
The short answer is no. If anything, Karlovic has shown himself far less likely than the average player to perform above or below his ranking. Last August, I created a metric called ‘Upset Score’ designed to measure how often a player wins against a superior opponent or loses to an inferior one. (Player ability is measured by my ranking system, which predicts match outcomes better than ATP rankings and considers surface.) The metric counts extreme upsets more heavily, so Ivo beating David Ferrer is scored as much more meaningful than defeating, say, Stanislas Wawrinka. Of the 87 players who had 40 or more ATP-level matches in the 20-month span I analyzed, Karlovic had the tenth lowest Upset Score.
This flies directly in the face of conventional wisdom. Looking at the current rankings, we find Ivo just below the likes of Santiago Giraldo and Olivier Rochus–neither one of whom would be viewed as a “tricky” third round opponent. Yet both have Upset Scores in the top half of active players. While there’s no doubt Karlovic was once a very dangerous opponent (as his peak ranking of 14 suggests), he has only one top ten scalp in his last twelve tries, dating back to 2009 Wimbledon. We have to go back to the first half of 2007 to find a stretch in which he was a consistent threat to top players.
Isner isn’t as predictable, but delivers fewer upsets than 60% of the guys on tour. Same story as with Ivo: more often than not, he wins and loses according to past performance. Big John has won two of his last fourteen matches against the top ten, and one of those was an ‘upset’ of Nikolay Davydenko, who by this metric is the least predictable man on the tour.
Massive servers may make for more interesting matches–against any opponent, it’s safe to say that Isner and Karlovic are more likely to deliver a tiebreak or four. But if you’re a top player deciding who you’d like to see coming up in your bracket, you probably don’t care whether you win 6-1 or 7-6(8). Whatever the score, Karlovic is best seen as a steady player on the fringes of the top 50, not some loose cannon who will knock out a top seed one day and lose to a qualifier the next.