I've been reading some articles on the 3-3-5. Almost none of them agree with what various posters are saying. Here's one.
"Conclusion
The 3-3-5 defense is a great option for coaches to run in today’s game of football.
It allows for great flexibility to defend against both the pass and the run, especially when more and more offenses are running more multiple wide receiver sets and out of more shotgun formations.
Perhaps the best thing about a 3-3-5 defense is its ability to cause confusion to opposing offenses.
Nearly every position at the second level (the linebackers) and the third level (the secondary) of the defense can be a potential blitzer, which means that pressure from a 3-3-5 defense can come from anywhere at any time.
This not only creates confusion with receivers running passing routes and offensive linemen trying to identify blitzing players, but it also causes confusion for offensive players when they’re trying to identify their blocking responsibilities in the run game.
However, in order to effectively run a 3-3-5 defense, a coach must first know whether he has the defensive personnel capable of the task.
Almost all players on the defense in a 3-3-5 formation must possess speed and quickness, along with strength up front and vision and adjustment ability in the linebackers and secondary.
The secondary must also have players capable of keeping contain and covering receivers one-on-one without extra support over the top at times as safeties and linebackers blitz.
Overall, if a coach has the right personnel that can understand and run the formation, a 3-3-5 defense is a great option for keeping opposing offenses on their toes.
It’s also a great way to teach players a different approach to defense and give them multiple tools they need to read offenses and react by either dropping into coverage against the pass, or blitzing and filling gaps against both the pass and the run."
https://footballadvantage.com/3-3-5-defense/
