I would say patience is a problem in MLB in general. When Moneyball led to everyone taking walks and working the count it made sense. The goal was to get a starters pitch count up so you could get to the bullpen which, at the time, was full of inferior pitchers compared to starters. Nowadays, relievers have better stuff than starters so forcing them into the game isn't really advantageous. There's also the fact that pitchers in general are just better than they used to be. Taking that first pitch fastball over the heart of the plate for a strike does the batter no favors when it's the best pitch they'll see.