And with that start ending in the team's fifth straight loss to start the second half, 5-2 to the Giants, that hole at the end of an otherwise solid four-man staff is festering.
Whether McDonald receives another start, Dodgers manager Joe Torre said, would depend on "where we are."
"For the most part I thought he threw the ball well," Torre said. "I know the numbers won't look good, but I was impressed with the way he threw the ball."
McDonald struck out five, allowed nine hits and walked two.
Early on, the 24-year-old right-hander's day seemed like it could go the way of his predecessor John Ely's final two starts -- an exit by the third inning. But McDonald worked out of a bases-loaded, none-out jam in the second inning, starting with a strikeout of Travis Ishikawa on three straight changeups.
"Just making big pitches when I needed to," McDonald said.
He wasn't out of the woods though. The Giants scored two in the top of the third, and two more in the top of the fourth on McDonald's worst pitch of the night, a changeup that hung above the belt for Nate Schierholtz, who made it 4-0 on his third home run of the season.
"I made good pitches at times, they put some good swings on the ball on good pitches," said McDonald.
"I thought he threw the ball good, but again, throwing the ball good isn't good enough if you don't locate it," Torre said. "I thought his stuff was good, his offspeed stuff, the slider which is a new pitch for him. But there were a couple of counts where he got ahead in the count and probably made his pitches a little too fat."
McDonald appeared in 45 games in the big leagues last season almost exclusively as a reliever and was a candidate for the fifth spot out of Spring Training this year, but he didn't perform well, and a hamstring injury took him away for a month earlier this season. He was 6-1 with a 4.41 ERA in 12 starts for Triple-A Albuquerque, and 4-0 with a 2.79 ERA in his last five starts before the callup.
Torre talked before the game about the success Ely had in his most recent start at Albuquerque, a three-run, seven-inning performance Sunday.
"Ely had a good night last night," Torre said. "And the report was he was very good. So you know we're at this point in the season now we look to get help from wherever we can find it. Try to get enough stuff on the left side of the ledger basically."
McDonald said he wasn't worried about whether he gets another chance: "If they call on me, then I'm going to go back out there."