For elite fighters, defense is much more important and should always be prioritized first.

There's an old saying that goes, "Offense sells tickets and wins games, defense wins championships"

For Basketball, NFL, Soccer, Hockey, Defensive teams mostly pull out on top and wins a championship.

http://bleedbigblue.com/wp-content/uploads/2012/10/Defense-Wins-Championships.jpg

Boxing is no different.

Defense needs to always be prioritized. Offense is important, but defense protects your faculties, protects you from having your head knocked off your shoulders, defense wins you fights, defense needs to always and I mean always be a boxer's #1 priority.

When you look at the superfights of the past, most of the times - defensive fighters win. That's a fact.

Ali/Foreman
Floyd/Pacquiao
Pernell/Chavez
Lewis/Tyson
etc