The two will meet in Saturday's Madrid Masters semi-final with Nadal looking to bridge the gap with Djokovic boasting a 26-23 head-to-head advantage.
However, the two haven't met since last year's Rome Masters, since when Djokovic has been displaced by Andy Murray as world number one and parted company with coaches Marian Vajda and Boris Becker due to his poor form.
"On his slump, 99 percent of players would love to be in his position," said Nadal.
"We have to analyse the numbers. In his dip after Wimbledon, he won in Montreal... made the final at the US Open, the semi-finals in Shanghai, the final in the World Tour Finals."
Indeed, Nadal claimed it is Djokovic's sensational form between 2011 and 2015 that was unusual.
"When you win every single match in every tournament, that is abnormal. In history we have never seen what he achieved during those years."
And the Spaniard sympathised with Djokovic's struggles to maintain the same level of consistency for so many years having been through the same experience himself.
"Let's respect his level right now because it's true that perhaps it's not as high as he used to be, but I can also tell you it's (been) a lot of years.
"I know because I've been in his skin, too. Being up there during every single week, being number one every single week, it's nearly impossible."
Djokovic has won the last seven meetings between but Nadal paid tribute to a great rivalry despite the damage the 12-time Grand Slam champion has done to him in the past.
"It has made me better. When you play people that are so good it always makes you give 100 percent.
"I think we have done damage to each other during our careers. We have taken plenty of titles from each other," Nadal added.
"The reality is that it's been a really good era because the matches between Djokovic, (Roger) Federer and me... we've made it many times to the final rounds, competing in the most important tournaments.
"I think it has made a lot of people to come watch tennis, so that's a very positive thing."