"We have to get him back to that," D-backs manager Chip Hale said. "He showed some pitches that he is, and then leaves a couple of balls up. We trust him in that spot. We're going to keep throwing him out there and he'll get better, I'm sure of it."
Marshall (0-1) was summoned to protect a 4-3 lead and he quickly retired the first two hitters he faced in the seventh.
Then the wheels came off.
Joc Pederson, who was 0-for-3 with three strikeouts to that point in the game, hit the first pitch he saw from Marshall over the wall in center to tie the game.
"It was a first-pitch fastball to Pederson," Marshall said. "He'd been struggling all night, but he got all of that one. The pitch had a lot of movement on it, but it was definitely down the middle. He's a dangerous hitter and you can't make mistakes like that to a guy with that kind of ability."
Justin Turner then doubled down the line in right and Howie Kendrick grounded a ball to the hole at second that just snaked under the glove of a diving Aaron Hill, who was shifted more up the middle.
Marshall had Kendrick down 0-2 in the count before throwing a pair of balls in the dirt. And when Kendrick got the ball through the infield that scored Turner, the Dodgers led 5-4. Marshall also had two strikes on Turner, but was unable to finish him off.
"You don't want to get out there and let things kind of snowball," Marshall said. "I gave up the home run to tie it and I wanted to just go out there and attack and get that third out. Turner was able to keep that ball fair and then the ground ball to Kendrick. It was frustrating but I've just got to keep attacking. I just need to execute a put-away pitch there to Kendrick and take advantage of an 0-2 count. I'm happy he hit the ball on the ground, but it was still an RBI single."
As a rookie last year, Marshall had a 2.74 ERA and as the year went on he began to be used in more crucial situations. This year, the results have not been there for him as his ERA is 7.45.
"Last year I was able to keep the ball down and especially make better pitches with two strikes," Marshall said. "That's what I'm looking for is that strikeout when I have the count in my favor. The stuff feels great. My velocity is good, the health of my arm feels good. I just need to read the hitter and make a better pitch. That's really all I can say."
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.