Dodgers suffer a rotational error as Dan Haren rocked in loss to Cubs

Dan Haren’s performance alone was reason for the Dodgers to be alarmed. Turns out that was only the start.

The Dodgers’ season-long winning streak ended at six games Friday night with an 8-2 defeat to the last-place Chicago Cubs that unfolded like a full-scale nightmare. Yasiel Puig and Adrian Gonzalez hurt themselves sliding home. Left-hander Paul Maholm also made an early departure from the lopsided loss, as he went down clutching his right leg after covering first base.

The Dodgers downplayed Puig’s and Gonzalez’s injuries, saying Puig was removed from the game as a precaution and Gonzalez was listed as day-to-day.

Puig felt discomfort in his left hamstring in the wake of an unnecessary sixth-inning play that reduced the Dodgers’ deficit from seven runs to six. He was on second base when Hanley Ramirez hit a grounder to third baseman Luis Valbuena, who flipped the ball to second base for the force out. As second baseman Arismendy Alcantara threw to first in an unsuccessful attempt to get Ramirez and complete a double play, Puig charged home. Puig reached the plate around the same time as the ball, but he managed to evade the glove of catcher Welington Castillo and scored.

Puig didn’t return to the field.

Gonzalez was hurt in the first inning, also on a sequence that started with a grounder hit by Ramirez. Dee Gordon, who was on third base, scored. Gonzalez, who was on first base, tried to do the same after Cubs shortstop Starlin Castro made an errant throw to second that ended up rolling down the right-field line.

Gonzalez was not only thrown out at the plate on the play, he also bruised his right knee. He was replaced by Scott Van Slyke in the top of the third inning.

But the real problems were on the mound.

The Dodgers turned to Haren again, a day after they were unable to acquire a starting pitcher before the non-waiver trade deadline.

Nothing about the start indicated Haren was about to return to his solid early-season form. Over 4 1/3 mostly laborious innings, Haren was charged with seven runs, including six that were earned. He served up eight hits, among them a solo home run by Valbuena in the second inning. The homer was the 20th allowed by Haren in his last 15 games.

The Cubs scored three times in the third inning to move in front, 4-1. Haren wasn’t entirely to blame, as the inning included a throwing error by Matt Kemp.

Haren was replaced by Chris Perez in the fifth, with his pitch count at 93.

In his last five starts, all losses, Haren has allowed 26 earned runs in 23 1/3 innings.

What Perez did served as a reminder of another problem the Dodgers failed to address at the deadline. Perez inherited three runners from Haren and all scored.

Haren’s uninspiring start became more of a problem in the seventh inning, when Maholm went down.

Maholm has started only once in the last two months, but would be the likely replacement in the rotation if the Haren or Josh Beckett is removed. Beckett has been pitching with an injured hip.

Maholm was able to walk off the field, but immediately disappeared into the clubhouse. Brian Wilson pitched the next inning.

dylan.hernandez@latimes.com

Twitter: @dylanohernandez