DENVER — Jeff Locke kept throwing the ball at knee level — or slightly lower — and kept getting the call for a strike.

That was much to his delight and the chagrin of the Colorado Rockies.

Locke threw six scoreless innings, Matt Joyce hit a three-run homer and the Pittsburgh Pirates beat the Rockies 6-1 on Monday night in a game that was briefly delayed by rain.

Locke (1-2) allowed five hits as he bounced back from a clunker in his last outing. He struck out a season-high eight, including five on called third strikes that were right at the knees.

“A few of them were generous,” Locke acknowledged. “A few of them could go either way.”

All those low strikes drew the ire of the Rockies, who weren’t too pleased with home-plate umpire Lance Barrett’s zone. Manager Walt Weiss was ejected after the fourth for arguing and outfielder Ryan Raburn followed in the six.

“I guess you can’t get mad anymore,” Raburn said. “They weren’t good calls. I guess he didn’t like me being upset with it and I got rung.”

Weiss was a little more diplomatic.

“You question balls and strikes and you’re usually going to get tossed,” Weiss said. “But it was the same zone for both sides. They dealt with it better than we did.”

Locke cruised through most of this game. His only rough patch was in the fifth when he faced a two-on, one-out jam. He fanned rookie Trevor Story and got Carlos Gonzalez to fly out.

“Fastball, command, the intent, the conviction, the execution, the changeup in offensive counts, sprinkled in some curve balls, he pitched very, very effectively,” Pirates manager Clint Hurdle said. “Big start for him.”

That’s quite a contrast to his last start when he allowed eight runs in three innings at San Diego. It looked as if his spot in the rotation just might be in jeopardy.

“You think more that you need to have a good outing for the guys in the clubhouse,” Locke said. “A good all-around team win.”

Chad Bettis (2-1) had his start moved up a day with Jorge De La Rosa under the weather. Bettis gave up four runs in 6 2/3 innings.

Joyce broke the game open in the seventh with his three-run homer to left-center off reliever Scott Oberg. That gave the Pirates a 5-0 lead and sent them to their sixth straight win over the Rockies at Coors Field.

The game was halted for 30 minutes by a downpour with two outs in the second.