The St. Louis Cardinals won 91 games in 2019. They underperformed their run differential slightly; by the Pythagorean method their 764 runs scored and 662 runs allowed should have produced a 92-70 record.
The Milwaukee Brewers won 89 games in 2019. They overperformed their run differential significantly; by the Pythagorean method their 769 runs scored and 766 allowed would have produced, basically, a .500 team at 81-81. (In fact, going by run differential, the Brewers should have been only one game better than the Reds, who scored 701 runs and allowed 711 for a Pythagorean record of 80-82.