Bumgarner, the San Francisco Giants ace, suffered a broken finger in his final Cactus League start. He has a 2.53 earned-run average against the Dodgers.
The Giants replaced him Sunday with another left-hander, one with a lower ERA against the Dodgers.
"He's pitched really well against us," Enrique Hernandez said. "It seems like he's got our number, but it's a new year."
Blach had the lowest strikeout rate among qualifying major league starters last season. His soft tosses keep hitters off balance, all the more of a risk for the Dodgers if their batters are amped-up for the opener.