It’s opening day for Major League Baseball, and the Mariners are back in action today hosting the Cleveland Guardians at T-Mobile Park. M’s faithful will tell you: there’s a lot to look forward to this season. But in the off-season, some of the biggest rule changes to the game came into play. The bases themselves are three inches bigger all around. Defenses can no longer move infielders to positions statistically optimized for stopping base hits. And probably the biggest change? A pitch clock designed to up the tempo and cut the downtime during at-bats.