Yes every game against a bad team is winnable. But you don't win them all, that's not the way it works, bad teams beat good teams all the time. The Dodgers recently got swept by the Pirates in LA. A group of hitters that hit .300 aren't going to go a combined 6 for 20 every single game. Sometimes they'll go 6/20 and win. Sometimes they'll go 10/20 win by a lot, and it'll be balanced out by games where they go a combined 2/20 and they'll probably lose that one it happens.
You're allowed to be frustrated, it is annoying in the moment, but it'll happen probably 20 or 30 times over a season so you should probably let it go quickly if you can. You're going to be very miserable if you let it annoy you for multiple days afterwards. By the time you finally get over it it'll happen again.