Stairs has been preaching this and it's taken hold, Phillies have gone from a team with one of the lowest average pitch per AB to one of the highest in the league.
But it's not as simple as it sounds -
1) a lot of hitters have to relearn their approach, that can take time
2) balance between patience and aggression, attack the first pitch, but only if it's the pitch you're looking for, too often players are looking FB in a certain spot but swing at a high FB or a breaking ball - that's the bad habit they have to break
3) requires bat speed, that's why Stairs has tinkered with a number of players to simplify their swing mechanics and increase bat speed - faster bat means you can wait longer and recognize the pitch before swinging/not swinging.
4) some guys just don't "have it," they just don't see the ball well and have to guess, only so much you can do with those hitters.
Hoskins pretty much had this down when they drafted him, they just tinkered with his mechanics to generate more power without messing with his basic approach.
Klentak (and this I think started before him with Almaraz) has said they want to acquire "players," not skill packages, that is, prospects who know how to play the game and are not just getting by with athleticism. You can teach some players, but it's a lot easier starting with someone like Hoskins. I think that's what they saw with Haseley. I think this has extended down to LA signings, we're seeing more LA players with plate discipline in the system these days.
Same with pitchers, how many fireballers who lack command ever develop it?
