It is extremely true that, in baseball, there’s no such thing as a must-win game until September at the earliest. The season is too long and the sport is too flukey to ever assign so much emotional weight to nine measly innings.
But there certainly are games that you REALLY, REALLY SHOULD win. And I would posit that when (1) you’re facing one of the worst teams in recent history, (2) said team starts a pitcher who has compiled an ERA of nearly 10 in just 20.1 total career innings, and (3) the next opponents on your schedule are the best team in the National League, the best team in the American League, and a team in your own division that’s virtually tied with you, then YOU REALLY, REALLY SHOULD WIN THAT GAME.