Lyles, the organization's minor league pitcher of the year last season, continued to take his lumps on Sunday in a 7-0 loss to the Los Angeles Dodgers.
"I just made mistakes throughout the entire game and they made me pay," said Lyles, a first-round pick by the club in 2008. "On Sellers' home run, I was trying to punch him out with runners on first and second and then just hung a mistake over the plate."
The rebuilding Astros were swept in a series of three or more games for the 11th time this season. They have dropped a season-worst six straight games and 13 of 16 since unloading outfielders Hunter Pence and Michael Bourn before the non-waiver trade deadline.
Houston's 38-83 record is the worst in the majors. The Astros trail NL Central-leading Milwaukee by a whopping 32 games — their largest deficit since ending the 1975 season a franchise-record 43½ games off the pace.
Dodgers starter Hiroki Kuroda (8-14) allowed five singles over seven innings, struck out six and walked one. The 36-year-old right-hander, who came in tied with recently demoted Astros left-hander J.A. Happ for the most losses in the NL, won for only the third time in his last 15 starts despite a season ERA of just 2.88.
Kuroda's last five victories have come in games in which he didn't allow a run, dating to his 2-0 win at Pittsburgh on May 11.
"I'm not really used to having this many runs. I'd much rather have it than not have it, but my approach to pitching isn't any different," Kuroda said through a translator. "I'm a starting pitcher, and I want to keep the game close. So the less home runs I give up the better, but it's not because of a lack of run support."
Kemp matched his career high with his 28th homer, a solo shot in the third inning after Navarro sparked the Dodgers' offense with a two-run shot in the second.
Aaron Miles, who didn't have an RBI in his first 25 at-bats against the Astros this season, ended that drought with a run-scoring single through the box during a four-run sixth.
Three batters later, Sellers chased Lyles with a drive into the lower seats in the left-field corner for his first three RBIs in the majors. It was the ninth big league at-bat for the 25-year-old shortstop from nearby Bellflower, who was promoted Friday from Triple-A Albuquerque when rookie Dee Gordon went on the disabled list.
"It was very special, exciting and emotional for me, my family and my friends who have been there supporting me ever since day one," said Sellers, whose father Jeff spent four seasons in the big leagues as a pitcher for the Boston Red Sox.
Sellers' teammates were certainly pumped — particularly Navarro, who surprised him with a shaving cream pie in the face from behind while he was doing a postgame TV interview on the field.
"All home runs are exciting, but you never really forget your first one," said Kemp, one of several players who urged Sellers to acknowledge the curtain call he received from the crowd of 36,339. "That's a good feeling. I know what it felt like to get my first home run. He's from this area and had his family here, so it was a special moment. I'm happy for him Hopefully, there's more to come."
Dodgers first baseman James Loney pulled off a slick unassisted double play at first base to end the fourth inning, making a leaping grab of Carlos Lee's line drive and spinning around to tag J.D. Martinez as he dove back to the bag.
NOTES: Four of Navarro's five homers this season have come in day games, one of them against Astros RHP Wilton Lopez in the eighth inning of a 1-0 victory on June 19 at Los Angeles. Kuroda also started that game and ended up with a no-decision after allowing just three hits in seven innings. ... Pitching at Dodger Stadium for the first time, Lyles walked his first two batters of the game — equaling the number he had in 32 1-3 innings over his previous five starts. ... The Dodgers' only other three-game sweep this season came against San Diego at Chavez Ravine in the final series before the All-Star break. The Padres and Astros, both last in their respective divisions, are a combined 92-151 and 46½ games out of first place. ... The Dodgers begin 10-game road trip through Milwaukee, Colorado and St. Louis on Monday night. 2B Jamey Carroll is batting a major league-best .344 on the road, compared to .253 at home.