Improved vastly or done the right thing all along?
When he first came to the club we were in a post-AVB&Sherwood shambles. Attitude, fitness, ability, style of play... It was all a mess and loads of uncertainties. Pochettino implemented a style of play, focused on the players with the right attitude, shifted the players that didn't fit and recruited well. When that style of play had been established and the squad was made up of the right kind of players he could start introducing more tactical flexibility. I think a large degree of single mindedness was a very good idea to get to the stage where flexibility was possible.
Not saying he hasn't learned or improved along the way. Not saying he hasn't tweaked or changed his mind at all. I just think it's unfair to judge his previous choices by what has worked at a later stage. We really have no idea if what he's doing now would have worked 2-3 years ago. And we have no idea what he considered and rejected, and for what reason, at different stages.