The Catalan giants have failed to live up to fans' expectations this season, having bowed out of the Champions League and Copa del Rey, as well as losing ground in the title race.
However, the ex-Portugal international believes that the best teams in the world often suffer short-term blips.
"It is difficult to say from the outside what is going wrong at Barca," he told Marca. "People talk a lot but, to me, what's happened is a normal and natural process.
"Barca have won a lot in recent years, they have been at a very high level - they were the best team in history for many people. And so it is normal what they are experiencing now."
Deco went on to say that Barcelona should work on rediscovering their top form gradually and dismissed the need for a radical overhaul at the club.
"The club should focus on rediscovering success slowly, keeping stars like Lionel Messi or Andres Iniesta who remain essential to the club," he added.
"There is no need to change the style because of two bad results, though. Barca already have a defined style and any reconstruction has to work within their existing form, as Louis van Gaal, Frank Rijkaard then Pep Guardiola did.
"Their style is to hog the ball and they're the best in the world at that."
Barcelona are currently four points behind La Liga leaders Atletico Madrid going into this weekend's round of fixtures.