CHICAGO -- There were gasps. There were sighs. There were groans. There were cheers. Wrigley Field was the orchestra. Oneil Cruz was the conductor -- for better and for worse.

With two waves of his bat, Cruz boasted the power that cannot be taught. With several rotations of his arm, Cruz displayed the shortcoming that can be corrected. The Pirates’ 4-2 loss to the Cubs on Tuesday, then, served as a benchmark of where Cruz stands and where he can still go.

“Overall, I'm learning a lot and just trying to make sure I'm growing in every aspect that I can,” Cruz said through team interpreter Mike Gonzalez.

The rookie’s highlight in the series finale wasn’t hard to find. Few people on this floating rock can punish a baseball as much as Cruz, and in two consecutive swings, he displayed how that strength can manifest.

With one hack, Cruz launched a ball 411 feet at 113.1 mph that approached North Sheffield Avenue. Foul ball. Gasps, then sighs. With his next swing, he smashed a ball 416 feet at 111.3 mph into the shrubbery that lay beyond center field. Fair ball, no question. Gasps, then groans. 

The homer was Cruz’s second in the last three days, the former of which came against All-Star and workhorse extraordinaire Sandy Alcantara. Cruz’s conquest of Alcantara was impressive because Alcantara had only allowed 0.39 home runs per nine innings, best among qualified pitchers. Dig into the minutiae and you’ll find the plate appearance may have been the best of Cruz’s burgeoning career.

Cruz was down in the count, 0-2. That’s not a fun place to be, especially against an elite pitcher. Cruz laid off a low changeup -- by Run Value, Alcantara’s changeup is the best in the game. Cruz laid off a borderline fastball, then fouled off a changeup. On the seventh pitch of the at-bat, Cruz turned on a high and inside 99.4 mph fastball and sent it into the right-field bleachers. Prior to that plate appearance, Cruz didn’t have a hit on a pitch that was high and inside.

“I just wanted to make sure I could find a good pitch, connect with a ball out front, and [just look] for a hit,” Cruz said. “I'm glad I was able to get a home run off it.”

Much has been said of Cruz’s brawn. Much has also been said of Cruz’s developing defense, a concern that, once again, arose following a smattering of shaky plays.

In the bottom of the sixth inning, Cruz fielded a routine grounder off Nico Hoerner’s bat and sailed the throw over the head of first baseman Josh VanMeter. Shelton said Cruz didn’t move his feet. Cruz added that his index finger got stuck in his glove, resulting in him throwing the ball with just his middle finger. Regardless, the helpless VanMeter could do nothing but remain glued to the earth. E6.

Overcompensation followed. The next play, Cruz collected Patrick Wisdom’s grounder and threw low, forcing VanMeter to drop into a squat. The next inning, Cruz shortarmed a standard throw that VanMeter had to pick out of the dirt. Shelton, again, noted that Cruz didn’t move his feet. The two-inning sequence was among Cruz’s worst defensive showings in the Majors to date.

It’s an area of Cruz’s game that he is actively seeking to improve.

An hour prior to first pitch, as the crowd began to file in for what may have been Willson Contreras’s final home game as a Cub, Cruz took grounders fed out of a pitching machine by bench coach Don Kelly. The emphasis wasn’t on receiving, but throwing.

Of the four errors Cruz has committed -- Monday night’s throwing error on Cruz was changed to a missed catch error on first baseman Michael Chavis -- three have been a product of his right arm. Cruz, yes, has a cannon. His 97.8 mph on July 14 is the hardest-thrown assist since Statcast began tracking in 2015. The lingering concern is consistent precision.

“I'm just trying to be better on defense, trying to become a master of my craft and trying to make sure I'm securing those routine plays,” Cruz said. “I'm just going out there trying to make sure I'm getting better.”

Cruz will have moments where he shines. Cruz will have moments where he falters. Such is the nature of rookiedom. And when these moments naturally unfold, Cruz will conduct a sea of sound from whomever stands before him.