"He just fell behind, walked a few guys and then just made a couple of bad pitches," D-backs manager Chip Hale said of De La Rosa. "Both were changeups, which is his go-to pitch. They just did a good job of hitting him, Turner and Joc Pederson. It's tough when you get four runs on one swing. It kind of put us out of the game."
The D-backs knew there could be nights like this when they acquired De La Rosa from the Red Sox in the offseason. The right-hander possesses electric stuff, but sometimes struggles to harness it.
While the Pederson homer was the big blow, it's worth noting that two of the three runners on base when he hit it got on via walks.
"I lost a little of my focus and location," De La Rosa said. "I tried to do too much that inning and make perfect pitches. When I try to do too much sometimes it doesn't work."
The type of pitcher De La Rosa could be was on display in his previous start against the Pirates when he allowed just one run on four hits and did not walk a batter over seven innings.
The D-backs could see the unraveling begin for him Friday, but were helpless to do anything about it.
"It was like a 15-minute period there where it did get away from him," Hale said. "We tried to help, we tried to go out there and talk to him. It's tough. That's just part of the learning process for him. He's had a hard time with those types of innings. They've gotten away from him and it did again tonight."
The D-backs bats, which had pounded out 25 runs in the three-game series against the Rockies this past week at Chase Field could do little against Dodgers starter Carlos Frias and a trio of relievers.
"Throwing 97 with a little bit of run and then a 92 mph slider," D-backs catcher Tuffy Gosewisch said when asked what made Frias so difficult to hit. "He was throwing the ball well. He made some good pitches. He's got good stuff. He's just a tough guy to hit."
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.