ST. LOUIS — Jason Hammel had a lot to do with the early 6-run cushion.

The pitcher went above and beyond in helping end the Cubs’ first three-game losing streak of the season with a 12-3 victory over the St. Louis Cardinals.

“Right out of the gate, took my first swings before I made my first pitch,” Hammel said after working 7? stingy innings and contributing a 2-run double to the Cubs’ big first inning.

Hammel has beaten the Cardinals twice this season, allowing 2 runs in 13? innings. This was his longest outing of the season, and manager Joe Maddon thought he could have thrown a complete game.

“It’s important for us, it’s important for him psychologically to be able to do that,” Maddon said. “It’s important that they know he can.”

Michael Wacha (2-5) gave up a career-worst 8 runs in 4 innings and has lost 5 consecutive decisions for the first time. The 24-year-old right-hander was a 17-game winner last season and the NL championship series MVP as a rookie in 2013, but this season has a 5.04 ERA.

“It’s a pretty discouraging start,” Wacha said. “I never really gave the team a chance.”

Jorge Soler drew a bases-loaded walk in the first and hit a 2-run home run in the fifth.

The 6-run inning was a season best for the NL Central leaders, who snapped their first three-game losing streak of the season. David Ross had an RBI double for his 500th career hit on a ball that somehow eluded center fielder Randal Grichuk’s glove at the warning track, and Kris Bryant had an RBI single in the outburst.

Hammel (6-1) bounced back from his first loss in his previous start, allowing 1 run on 4 hits and retiring the side in order five times. The 2-run double gave him a career-best 5 RBI on the year and his sixth hit in 23 at-bats.

“Nice, let’s focus on that,” Hammel said. “And I’ve got four months to go.”

The outing was his longest since throwing 7? innings against the Los Angeles Dodgers on June 23, 2015. He’s 6-1 for the second time in his career, also doing it in 2012.

“Honestly, I really wasn’t that good tonight,” Hammel said. “I got away with a lot of stuff.”

Wacha had no losing streak longer than three games before this season. In his last 3 outings he has allowed 20 runs, 16 earned, in 12 innings with all three lasting 4 innings.

“When the season broke he was as good as anybody,” manager Mike Matheny said. “He found a real good spot and we know what it looks like when he can get into a good rhythm.”

Pinch hitters Tim Fedorowicz and Matt Szcur had an RBI apiece in a 4-run ninth off Dean Kiekhefer.

• The Cubs have won Jake Arrieta’s last 22 starts, a franchise record. He’s 19-0 since his last loss on July 25, 2015, against Philadelphia. Arrieta takes his major-league leading 1.29 ERA and .153 opponents’ batting average into today’s start against the Cardinals to wrap up the road trip.