No it is not. We are stacked in defense and Nastasic is by no means a guarantee. Since effective defense is very much coach dependant we must wait and see how Allegri manages to work with the quality material he inherited from Conte but this is a completely different issue.
On the other hand the flair and fancy department is the single reason why we are so far behind the top teams. It is clear as day yet some people still argue otherwise.
Just of the top of my head, creative and pacy players in top European clubs (CF not included - I believe with Llorente and Morata we are pretty good here)
Real: Ronaldo, Bale, Di Maria, James, Isco,
Barca: Messi, Neymar, Suarez, Iniesta
Bayern: Robben, Ribery, Muller, Shaqiri, Gotze
Chelsea: Hazard, Oscar, Willian, Schurrle
City: Aguero, Jovetic, Navas, Silva, Nasri
Man U: Mata, Kagawa, Januzaj, Rooney, Herrera
Arsenal: Sanchez, Oezil, Cazorla, Oxlade-Chbmbarlain, Walcott
Juve: Tevez, Giovinco, Pepe, hopefully Coman, maybe Pereira
This comparison is just hearbreaking and anyone who argues that we lack defenders more than pacy and creative attackers just doesn't know about football.
The type of players we lack are the most expensive and sought after players so it comes as no surprise we are so much behind the rich teams taking into consideration our limited budget. For this reason, however, we must do our best and try to improve here instead of spending the scarce funds we have on yet another defender.