It hasn't been service as usual for Roger Federer this year. Two semifinals and a quarterfinal in three events played isn't quite up to his usual standards, especially compared to the two titles and a semifinal he picked up at the same tournaments a year ago.
Part of that is because he hasn't been serving as usual, either.
Looking at the big picture, it's not that easy to tell. His first-serve percentage for the season so far is 63 percent, a little above his career mark of 62 percent (and 61 percent on hard courts). But the number has fluctuated wildly, and he has frequently struggled to find his mark at important moments.
In the Australian Open semifinal against Andy Murray, for example, Federer's first-serve percentage for the match was 61 percent -- but not in any given set.
In the first set, it was 58 percent, then somehow 75 percent in the second, then 54 percent for the third, 58 percent in the fourth, down to 54 percent again in the fifth set. Did it determine the outcome of the match? Hardly, but it didn't help.
It was a similar story during Federer's five-set win against Jo-Wilfried Tsonga in the previous round, where his first-serve percentage was again 61 percent, but went from a low of 55 percent in the first set to a high of 69 percent in the fourth.
Some early signs of this deterioration had begun in the fourth round against Milos Raonic.
It didn't show in the scoreline -- Raonic is not known for his return and was hampered by a foot problem -- but Federer didn't produce the same pinpoint deliveries during that match that he did during his third-round contest against Bernard Tomic, when he got in 69 percent of his first serves. The quality of his second serves also dropped subsequently, many landing shorter and with less angle.
At least his service speeds didn't appear to suffer at all match to match, remaining at an average 185-187 kmph on the first serve and 157-155 kmph on the second (with the fastest serve between 205-207 kmph). But for a player who relies as much on placement and variety as power, even a slight loss in accuracy is significant. Especially when combined with his notoriously low break point conversion rate against tough opponents.
When looking at player performances, the serve is the easiest stroke to examine in isolation. While outside factors like wind and the quality of an opponent's return can have an effect, it remains the shot over which the player has the most control. It can also often be the most important -- it starts each service point, and often sets the tone for the rest of the performance.
Serving fluctuations are nothing new for Federer, particularly against other top players -- last year, he went from getting 73 percent of first serves in during the quarterfinals of Cincinnati, to 54 percent in the semifinals, and was struggling to get out of the 50s throughout the French Open as well. And with so much game to back it up, he can frequently get away with it -- he has still won 90 percent of his service games so far during the season.
But it has been costly at key moments, like the weak second serve that allowed Murray to go on the offensive at break point at 1-1 in the first set and take the early lead in Melbourne.
Federer's first-serve percentage against Julien Benneteau in Rotterdam was 54 percent, and serving to stay in the match, Federer missed four out of six first serves, including one that ended with a double fault. "If you lose your serve five times like I did today, you can't win indoors," he remarked.
In Dubai, Federer had three match points in the second-set tiebreak against Tomas Berdych in the semifinals -- the third on his own serve -- but Berdych was able to hammer the return and escaped with a win.
"I think I didn't serve great overall toward the end of the second set, and I think that showed in maybe that moment," said Federer afterward.
After a period of cleaning up on faster surfaces a year ago, the inconsistency is costing him in similar conditions now.
"The thing is, if you don't serve well on this court early on in the game, you don't serve well to get yourself out of trouble, things will go awful," he said of the quick Dubai courts. ''They'll look like you're flat, they'll look like you're not playing well, they'll look like there is no rhythm, which there isn't much. So if you go into a tough 0-30 hole, it's tough to get out of it, you know."
Overall, Federer has not been playing poorly -- a few error-prone patches and scratchy starts, but still a high level of play and some clutch tiebreak performances during the Australian Open. Whether his recent problems end with the serve or not, it's clear that's where a lot of them have started.
"I've definitely got to work on that," Federer resolved before leaving Dubai, and also expected to be able to get away with it a little more over these two weeks. "Indian Wells is going to be much slower, so it's going to be a different type of tennis," he said.
Federer benefiting from slower hard courts? Now that would be serving up something unexpected.