I disagree on some of your assessment of the problem with the clatter defending. I think there's several other issues.
1) No players (outside of maybe Messi, Neymar, Robben) move with their respective real life agility. Chico Flores is a pretty nifty defender for a CB, IRL, so how is it I get caught in possession with him just trying to turn and pass in defense? This leads to increased "blitzkrieg" defending because it is so much harder to pass around that style of play than in real life. Additionally, passbacks to the keeper are incredibly dangerous and result in you having to 1 time it all the way down field or risk getting caught with it by a blitzing striker applying pressure. Friendly defenders don't drop to make themselves available on the wings like you see in real life.
2) Offensive AI still isn't smart enough to simply run into space. The runs that are made are generally regardless of the available real estate, nobody really seems to float into ungoverned pockets of space. So while in theory, barnstorming defenders should be leaving huge gaps, rarely are your compatriots actually moving into those gaps. This is never more exemplified than if you play a ball into space in front of a winger on the attack. 9/10 times, NOBODY comes to his aid. Nobody is in that massive gap triangle between the fullback, centerback, and trailing central midfielder, even if you're playing with 5 midfielders and a striker. The AI doesn't make the run with a central player that we can make in pro clubs (for OU to ignore in favor of steaming into the defender).
3) As @
pavel despises, there is really no penalty for running guys to death trying to apply pressure. In real soccer, "pressure" is usually applied by approaching the player in possession while occupying a primary passing lane. In FIFA you don't need any such tactic, just a fast player to harangue the other team's defense and DMs. You can use up all the stamina and it barely matters (and you basically have 3 stamina-based subs - rarely do pubers actually sub to change tactics because everyone uses the same fucking tactic).
4) Similar to 3, there is no drawback to slamming into opposing players, because you can't quickly work around them very easily.
5) More fouls. They need to increase the amount of outcomes from physical contact that isn't initiated by an explicit tackle (using the slide or standing tackle).
6) Nerf the effectiveness of the counter-attack. Everyone I play now who uses Mexico runs that 5-3-2, sits ultra defensive, and just hopes that Giofaggo or Chicajoto can break free. The same goes for most Brazilian teams, and Colombia - sit ultra-defensive and just hope for a loose ball that you can launch downfield to Retardelli, Cuadrado, etc. Defensive AI needs to be improved to cut down these angles. Why is my fullback even letting these jokers get so wide to start with?
There's other issues too. I think the easiest fixes would be implementing real fatigue based injuries. Not that hamstring pull in the 88th minute, but like a guy who is run ragged taking a foul in the 70th and having to leave the game. Significant fatigue should also drastically diminish strength and overall speed, not just the length of time you can sprint. Additionally, sliding tackles should either be slower, take more time to get up from, or just generally not be as accurate. Lots of pubers use sliding behind the guy receiving the ball as a "legitimate" (in that it works) tactic online, rarely pick up cards, and don't leave a whole lot of space.