The Italian acknowledges that Lionel Messi is a “phenomenon”, that Neymar is improving and that Luis Suarez is the kind of centre-forward that the Camp Nou outfit have been crying out for.
He is, however, of the opinion that Luis Enrique’s side have failed to address issues in the middle of the park.
In contrast, Capello believes that the recruitment by his former employers at Santiago Bernabeu has been largely positive.
"The problem for Luis Enrique is the centre of the park,” he told Corriere dello Sport.
“He has an incredible attack, but in midfield he doesn't have Xavi - who has never been properly replaced - and Iniesta has suffered injuries.
"On the other hand, Real Madrid have made very good signings and above all picked the time to do it well, while Barcelona haven't reinforced their squad as they may have liked to."
He added on Barca’s MSN attacking unit: "The three are excellent in terms of quality and creativity, but above all they provide the perfect mix of attributes.
“[Luis] Suarez is the centre forward that Barcelona had been looking for for a while, Neymar has improved a lot and [Lionel] Messi is the same phenomenon as always. This front three is frightening."
Capello will be an interested observer when Barca take on Juve in the quarter-finals of the Champions League, having spent many productive years in Turin during his playing and coaching career.
“They will need to be alert, and above all they need to make sure that they play until the final whistle. They know what happened to PSG."