Yes, bigger bases make it easier to steal bases. Yes, the Diamondbacks are speedy and steal a lot of bases. But their real supernatural talent is preventing stolen bases.
Through 27 April, their 0.27 stolen bases per game was the lowest in the Majors. And if Madison Bumgarner had left the team before the season started, then their 0.15 stolen bases per game would have been lower than any season as far back as I could look in Team Rankings (2007). The season lowest was 0.18 stolen bases per game by the 2020 Cardinals.
Although preventing stolen bases is a team effort (includes catcher, second baseman, and pitcher), the conventional wisdom is that bases are stolen off pitchers, not catchers.