"Players attacked him and he didn't go after them enough, he was too passive" - Strategy coach Craig O'Shannessy on Rafael Nadal's struggles at Wimbledon

ATP strategy coach Craig O'Shannessy recently explained why Rafael Nadal's results at Wimbledon were not up to the mark. According to O'Shannessy, the Spaniard is too passive when playing on grass, a surface that requires a more aggressive playing style.

Since winning his second Wimbledon title in 2010, the Mallorcan has only reached one final in eight appearances. Although he has progressed to the semifinals twice, Nadal has fallen twice in the second round and once in the first round.

Three of those losses came against players ranked outside the top 100 -- Lukas Rosol (2012), Steve Darcis (2013) and Dustin Brown (2015).

Speaking on the latest episode of the Court-Side with Beilinson Tennis podcast, O'Shannessy remarked that the World No. 4 lost because he did not take the fight to his opponents. The Australian pointed out that the former World No. 1 ought to have attacked more by coming to the net.

"You got Rosol that beat [Rafael Nadal]. You got Darcis that beat him. You got Dustin that beat him. I think overall, when Rafa will sit down and look at those matches, [he'll see that] players came at him," O'Shannessy said. "Players attacked him, they went after him and he didn't go after them enough. I think he was too passive. I think he didn't come to the net enough."

Craig O'Shannessy said the 35-year-old's usual approach might be better suited to clay and hardcourt, but on grass, Nadal should be looking to be much more offensive.

"I think that he let the guys do their stuff against him too much. He didn't assert himself out there as much as he could have," O'Shannessy said. "I think it's a matter of backing the foot off the pedal, putting the ball back into play and letting [the other] guys make a mistake like on hardcourts and clay. He just got on the wrong side of that. He just didn't play his best grass court tennis."

I was able to show Dustin Brown exactly how to play against Rafael Nadal, what to expect from him and where to attack: Craig O'Shannessy

Craig O'Shannessy revealed how he advised Dustin Brown to exploit Rafael Nadal at the 2015 Wimbledon

Interestingly, one of the architects of Rafael Nadal's shocking loss against Dustin Brown in the second round of the 2015 Wimbledon Championships was Craig O'Shannessy himself.

The Australian shed some light on how he made it happen, revealing that he advised Brown on exactly how to attack the Spaniard. Although the plans came from him, he gave the lion's share of the credit to the German for executing to perfection.

"Dustin [Brown] did beat Rafa at Halle. But when we get to Wimbledon, [Rafael Nadal] is the heavy favorite. However, Dustin does what Dustin does. A lot of what he did to win that match was already set in his DNA," O'Shannessy said. "What I was able to do was show him exactly how to play against Rafa, what to expect from him and where to attack. And he did that extremely well. He nailed it."

O'Shannessy noted how Dustin Brown neutralized the 21-time Grand Slam champion's sliced serve by positioning himself in a way that put him on the front foot from the get-go. The Australian recalled how he analyzed the former World No. 1's game to the point where he could anticipate every move and relay it to Brown, who then used the information to pull off the upset of a lifetime.

"[Rafael Nadal] loves the slice serve down the T. So Dustin, instead of putting his left foot on the singles line, puts his right foot. So the slice now is coming forward at him. I studied Rafa so much, he hits everything so meticulously," O'Shannessy said. "I know what he is going to do. He does the same things, so I showed it to Dustin. He absorbed it, and he went out there ultra confident."