"I personally struggle with lefty serves," said American Sam Querrey, in quotes given to USA Today.
This is simply a fact of life. If you're a righty, chances are you are not very experienced against southpaws and don't look forward to slice serves out wide in the ad court or down the middle in the deuce court.
Nadal has always used his serve effectively to open up the court for his forehand. However, as Douglas Robson notes in USA Today, pre-2010, if his serve "wasn't exactly a liability, it wasn't something opponents feared. It lacked pop. Some saw a slight hitch. It was attackable." This was especially the case on his second serve.
However, in Nadal's quest for his career Grand Slam, he put some serious work in his serve. In the U.S. Open 2010 tournament alone, his serve went up on average 12 mph from 2009. The video above shows just how big Nadal was serving to finally win the U.S. Open.
This year, in the final of Roland Garros, Nadal was serving only, on average, 111 mph. In addition, he's also only managed 104 aces this year, in comparison to Federer's 201 or Isner's 380. But, he's still managed to win 73 percent of points when his first serve has gone, not far off from his 75 percent won in 2010, according to atpworldtour.com.
We all know what he's accomplished in the last few months following his injury, and there is no doubt that his serve continues to play an integral role in his recent dominance (with an exception being this year's Wimbledon).