When Chicago Cubs reliever Scott Effross first learned his sidearm delivery, he watched a lot of hitting videos.

Because he uses more lower-half load than a conventional pitching delivery, his process more closely resembles a hitter’s. Dissecting those hitting videos became a valuable tool, helping him tap into his lower half more while using his hips and core to get down the mound and keep his arm path consistent.

“I’d see how guys would stay on their back legs and drive through,” Effross told the Tribune. “Obviously pitchers use their lower half really well regardless, but for me, that was probably the biggest adjustment, learning how to use that in a completely different way.”

Nearly three years ago, during the Double-A Tennessee All-Star break, Effross committed to the new sidearm delivery in hopes of changing his career trajectory. Effross, 28, has quickly become a versatile bullpen option for manager David Ross. Effross leads the Cubs with 19 appearances, owning a 2.04 ERA, team-high 11.5 strikeout-to-walk ratio and 203 ERA+. His 17⅔ innings are most among their relievers aside from the multi-inning, spot-start work of Keegan Thompson.

None of his 10 inherited runners scored. Only 14 MLB relievers had a higher WAR than Effross’ 0.5. He gives the Cubs a different look: Effross has the seventh-lowest average release point — 3.67 feet above the ground — in the majors. The average is 5.82 feet.

“If you were to ask me three years ago this is where I’d be now, I’d say that’s better than best-case scenario,” Effross said. “I still feel like I have a long way to go. There’s still things I’m learning every single day about the motion and how to attack hitters and just being a big-league pitcher in general.”

Through the first 2½ years of his new delivery and arm slot, Effross thought about his mechanics and how the process felt every time he threw the baseball. Now he’s at the point of fine-tuning, establishing better consistency and making adjustments.

Effross credited assistant pitching coach Daniel Moskos for helping implement small mechanical adjustments. Early in spring training, Effross’ posture became too bent and didn’t have enough lower-half load. It was caught quickly, and Effross got on track heading into the season. Repeating his release point has been a big part of Effross replicating mechanics.

The Cubs have been willing to use him in spots ranging from one batter (four times) to pitching in two innings (four).

“He can do so many different things, he’s not fazed by the moment,” pitching coach Tommy Hottovy said. “He can do a lot of different things. But it all comes back to just the consistency of the work for him and him being able to be himself no matter what that situation is.”

Figuring out how to balance platoon splits for a low arm slot is important, especially with the three-batter-minimum rule in place. Being competitive against left-handed hitters is a must. Effross’ changeup has become an important piece to his four-pitch mix. He averages 47 inches of vertical movement with his changeup, according to Baseball Savant; the league average is 31 inches.

His success against left-handed hitters this season — 0-for-18 with eight strikeouts and one walk — marks a big step in his development.

“What’s unique about his is just the amount of depth that it gets,” Moskos said of his changeup. “If you compare movement profiles, it’s like a left-handed slurve. It’s moving like a left-handed breaking ball, not like a right-handed changeup, which left-on-left breaking balls tend to perform pretty well. So it’s something that is really unique to the arm slot, and the pitch moves a ton. It’s really sharp, and that’s why he’s had success with it.”

The more Effross throws his changeup, the more comfortable the right-hander has become with going to it on any count and utilizing the pitch off his four-seam fastball. He has not given up a hit off his changeup (or fastball) this season, an offspeed pitch he has predominately used against left-handed hitters.

Veteran catchers Willson Contreras and Yan Gomes have helped Effross know when to best incorporate certain pitches given the situation.

“At the end of the day, these are big-league hitters, but you’ve got to look and see what they’re giving you and judging swing to swing,” Effross said. “Willie and Yan have been huge for me. They see something in a swing and they’re like, oh, we can capitalize on this and take a little bit of the thinking out of it for me.”

Baseball is a game of constant adjustments. With more data and information on Effross, look for hitters to adjust in the coming weeks to his delivery and how he uses his pitches. At least that’s what should happen. But Moskos noted that teams typically don’t game plan their lineups for an outlier reliever, which Effross and his low arm slot present.

There aren’t many big-league pitchers who give the same look as Effross, further making him an important bullpen option for the Cubs.

“Most teams are trying to adjust by just not swinging, but he throws strikes so that you can’t take that route with him,” Moskos said. “That’s the hard part, like, he’s just coming right after you. So it will be interesting to see because obviously the league makes adjustments to you, but I’m not sure what the adjustments are going to be just yet.”

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