It's not your openings. And it's not that you need to grind another 1,000 tactics puzzles.
It's this: you've been collecting moves when you should have been collecting ways of thinking. You reach a middlegame, the memorized theory runs out, and suddenly you're on your own — guessing.
The champions never guessed. Steinitz didn't attack until the position had earned it. Capablanca traded into endgames he'd already won in his head. Petrosian smothered your plan two moves before you found it. Carlsen just kept squeezing until opponents beat themselves.
Every one of them had a system for deciding what to do when there's nothing obvious to do. That's the entire difference between them and everyone else. And here's the good news:
A thinking system can be studied. Copied. Stolen. That's exactly what this book helps you do — champion by champion, game by game, for 30 days.