Predictions are, at best, educated guesses. Every year, the best minds in baseball reporting look at the way teams performed the previous year, look at the moves they made in the offseason to improve, and try to assess how well all 30 squads will fare in the new year. It’s not an exact science by any means, and there are always teams that go on to defy expectation (I’m looking at you, 2017 Twins), but by and large they offer a good overview of where the cards might fall.
Statcast guru Mike Petriello actually created a metric to see how many potential wins were gained and lost in the offseason based on moves the team made.