PITTSBURGH -- When the bottom of the fifth ended, Mitch Keller ascended the steps of the third-base dugout, jogged to the miniature mountain of dirt and prepared for another inning of Sunday labor. He’d have the sixth inning. He’d pitch the sixth inning. He’d finish the sixth inning. What once was the outlier is becoming the mean.

Keller churned out a third consecutive quality start in the Pirates’ 6-5 loss in 10 innings to the Marlins at PNC Park. Across six innings, Keller allowed three runs with seven strikeouts to no walks, going head-to-head with an All-Star in Sandy Alcantara. In his first three seasons, Keller couldn’t consistently provide this type of length. His day was often done once the sixth inning rolled around. Now, starts such as these are becoming the standard.

“I think we're seeing the next evolution of him as a starter [and] his ability to execute,” manager Derek Shelton said. “The one thing that has plagued him in the past has been high pitch-count innings. … I think he's getting to the point that he's more consistent, especially since we've gone to the sinker.

Consistency. Efficiency. Sinker. Add in the element of aggression, of pace, of tempo, and these are ingredients that have yielded Keller’s latest batch of success.

Since June, Keller has pitched at least six innings in six of his nine starts. For comparison, in his first three seasons, Keller only had three starts in which he pitched six innings. Every five days, Keller is, simply put, providing the Pirates with an opportunity to win. Given how he’s thrown the ball, there might be more six, seven-inning outings in store.

"Just using all of my pitches, especially the sinker and the slider,” Keller said of how he’s getting deeper into games. "Using the four-seam here and there early in counts and late in counts for strikes. Just having a good plan going in, attacking the zone, trying to get [outs on] three pitches or less. Trying to get these guys on the ground. Especially the sinker. I think it's made it a lot easier for me to do that. Just early contact is what I'm looking for. If the strikeouts come, they come.”

Keller may not be actively seeking the strikeout, but he wound up with quite a few early on. Three of Keller’s seven punchouts came in the fourth, which was easily his most impressive inning of the game and potentially the most impressive of the entire season.

The right-hander struck out Miguel Rojas and Avísail García swinging but froze Jesús Aguilar on ​​​​a filthy slider that appeared destined for Aguilar’s shoulder, then broke back in the zone before crossing the plate. Aguilar momentarily disputed the call before electing to recede.

On the subject of the slider, Keller has varied the pitch’s speed depending on the situation. In recent weeks, Keller has talked about taking ticks off his slider when trying to throw the pitch in the zone. By contract, Keller can throw the pitch with a little more force when he has the chance to record a strikeout. On Sunday, Keller threw his slider as hard as 83.8 mph, but as soft as 80.6 mph. For Keller, it’s all situational.

“Earlier in the count, trying to get ahead, throw strikes, it can be a little slower. That's not something I'm mindful of when I'm out there. It’s more of the mentality of trying to throw it over the plate for strikes. With two strikes, you're trying to put guys away. It’s just throwing a little harder and make it move a little bit more."

“I think the ability to add and subtract [velocity] to it is extremely important," Shelton added. "We saw up to [97.2 mph] with the fastball today, and then when you can vary the slider, it’s really important because you’re getting different looks. The fact that, especially with a pretty heavily right-handed lineup, you show them two different variations of the speed, then you have the ability to get them in between.”

Keller finds himself in the midst of an impressive run that has spanned the last three months. Since May 18, the hallmark day in which he introduced his sinker to the world, Keller has a 3.47 ERA across 62 1/3 innings. He is finally finding the consistent results that had eluded him in the infancy of his career.

The Pirates are working toward playing meaningful baseball in October. To get there, they’ll need pitching. They’ll need starters who can shove, who can provide length, and Keller is increasingly looking capable of checking those boxes. As one month gives way to the next, starts like these are ceasing to qualify as aberrations. They’re becoming the standard.