PHOENIX -- Young right-hander Randall Delgado stepped on the mound against the D-backs on Sunday and quickly showed why the Atlanta organization has such high hopes for him.It also didn't take him long to remind everybody that he is far from a finished product. Delgado was effective but could not overcome a few costly mistakes as the Braves dropped the series finale to the D-backs, 6-4. The loss snapped a five-game winning streak for the Braves, who have won 10 of their last 12. Whether Delgado will get another start before injured right-hander Tim Hudson returns from the disabled list and joins the rotation is to be determined. Tommy Hanson will start Friday against the Pirates after Thursday's off-day, but Atlanta has not announced the rest of the rotation for the weekend series. It's also apparent that Delgado has some work to do. His biggest lesson learned on Sunday was both valuable and painful: Never walk the pitcher, especially with the bases loaded. Delgado's teaching moment came with two outs in the second inning and his club ahead, 1-0. He retired D-backs catcher Miguel Montero for the first out of the frame and struck out first baseman Paul Goldschmidt for the second. The next hitter, Jason Kubel, followed with a sharp single through Delgado's legs with a 0-2 count, and that wasn't even the most noteworthy hit of the inning. "I was not trying to get that close to the strike zone, but I left the ball right in the middle, and I never thought that was going to happen," Delgado said. "It was a little frustrating at the moment." D-backs third baseman Cody Ransom followed with a double to move Kubel to third base, and Delgado intentionally walked John McDonald to set up what appeared to be a mismatch against D-backs pitcher Ian Kennedy with the bases loaded. It wasn't. Delgado walked Kennedy on four pitches to tie the game at 1. "I was trying to be too perfect with the strike zone, and that was a big mistake," Delgado said. "But what can you do? I did it. I can't do that again." It got worse before it got better. The right-hander's first pitch to the next hitter, Gerardo Parra, was a ball, and the next pitch was a game-changing fastball that Parra deposited into the seats in right-center field for a grand slam to put the D-backs ahead, 5-1. "I was trying to be down in the zone, but I made another mistake," Delgado said. "I left the ball up, and that happened." Delgado struck out second baseman Aaron Hill to end the eventful second inning, but the damage had been done. The hard lesson had been learned. Delgado offered a clinic in efficiency in the first inning, needing only 12 pitches to retire the side in order before he allowed the D-backs to school him in the second. He also gave a lesson in resiliency by not allowing another hit before he was replaced by Chad Durbin with one out in the sixth after striking out Montero and issuing consecutive walks to Goldschmidt and Kubel. In the end, Delgado was charged with five runs on three hits in 5 1/3 innings for his first loss of the season. He struck out six and walked four batters. "He got two quick outs in that one inning. He gets two strikes on Kubel and walks him. And the next thing you know, there is a five-spot put on the board," Braves manager Fredi Gonzalez said. "It's just a young pitcher that needs to mature and get in those situations and not let the inning get away from him. I like the way he went about his business after that, though." Martin Prado drove in a run, Freddie Freeman plated a pair and Juan Francisco provided hope with a solo shot in the ninth, but Atlanta's offense, which had outscored opponents by 37 runs in 11 previous games, could not overcome the early deficit. "I thought Randall showed everybody a lot today about his mental makeup," Braves second baseman Dan Uggla said. "He had a few mistakes that one inning, and that's all they got. He bounced back and battled and gave us a chance to come back and win the ballgame."