CHICAGO -- Summer Camp afforded the Cubs' batters a rare opportunity to get a pile of at-bats against their own pitchers. Slugger Kyle Schwarber came away from those battles blown away by what he saw from Chicago's relief corps.

"I was wowed facing these guys," Schwarber said. "I was like, 'Man, you guys can throw this hard in Spring Training? Where'd this come out of now?' I think we're going to see the best out of these guys. Don't sleep on this bullpen."

• Box score

Those glowing comments came in the wake of Saturday's 8-3 loss to the Brewers, who knocked Yu Darvish out of the game after the fourth inning and then pounded out five runs against Cubs relievers. The plus stuff that Schwarber raved about was present, but the results were not, and that can be a problematic recipe in a 60-game season.

In a typical 162-game season, a team can use the first couple of months to get a good read on its bullpen (often the most volatile aspect of any team's roster from year to year). Last year, for example, it was not until the second half that Rowan Wick and Kyle Ryan were fully entrenched as trusted setup men for the North Siders.

The window for evaluation has shrunk under 2020's unusual circumstances.

"You've got to get guys in there and see how they look," Cubs manager David Ross said. "[They’re] still learning, still pitching, still continuing to try to execute pitches. I think growth is going to be a strong point for that group.

"There's no way to find out until we get them in there."

Here’s a look at who got in there on Saturday:

Fifth inning: Duane Underwood Jr.
Underwood -- one of the standouts in Summer Camp -- took over for Darvish with a 3-1 deficit and featured 17 pitches. Per Statcast, the right-hander topped out at 96 mph with his fastball, got whiffs on two of six changeups and flashed his refined knuckle-curve once. Justin Smoak saw one change, one curve and then yanked a heater above the zone out to right for a one-out solo homer.

"There was some first-time adrenaline," Ross said. "Duane gave up that home run to Smoak, but he looked really sharp other than that one pitch."

Sixth inning: Brad Wieck
The three-month shutdown period was beneficial for the left-handed Wieck, who underwent a heart procedure in February. He had time to recover and build through a throwing program, winning a job on the Opening Day roster. Wieck allowed a two-run homer to Christian Yelich, and the reliever's average fastball velocity was down to 90.4 mph (compared to 93.7 mph in 2019).

"Yeah, that's something that we're paying attention to," Ross said of Wieck's fastball. "He's been about 89-91 throughout this mini camp. He is coming back from some medical stuff, so we've just got to continue to monitor that and continue to communicate with him."

Seventh inning: James Norwood
Norwood boasts one of the best fastballs in the Cubs' bullpen, and he showed it off against Milwaukee, maxing out at 98.5 mph, per Statcast. The righty pairs that with a splitter and slider, but the Brewers tagged him for three straight one-out hits and two runs before he escaped with an inning-ending double play.

"He’s made himself a lot better over the course of the last year," Cubs president of baseball operations Theo Epstein said recently of Norwood.

Eighth inning: Rex Brothers
Epstein said the 32-year-old Brothers had the backing of the front office as the team was constructing the Opening Day 'pen. The lefty has not pitched more than 23 2/3 innings in an MLB season since 2017, but he flashed a powerful fastball and swing-and-miss slider in camp. On Saturday, Brothers hit 97.4 mph, got six swinging strikes and struck out two in one shutout inning.

"It is real stuff down there," Ross said of Brothers on Thursday. "He's come into our camp and done nothing but prove himself."

Ninth inning: Dillon Maples
Ross pushed for Maples to be on the Opening Day roster, and the righty looked overpowering on Saturday, topping a 3,000 rpm spin rate on his slider six times. In 2019, Maples had the fourth-highest average slider spin (3,024 RPM) in the Majors (min. 100 sliders), but command has always been his obstacle. He faced the minimum with a strikeout in his '20 debut.

"Another guy with wipeout stuff," Epstein said. "One of the best sliders in the game. Still rounding out some of the hard edges of his game and has some continued development. There's a real upside there."

What the Cubs need now is for the upside to quickly lead to results.

“There's some electric arms in our bullpen with some absolutely plus secondary stuff,” Schwarber said. “I think the more that they're going to be getting in there, the more that they get comfortable, I think you're going to see the best of these guys."

Up next
Right-hander Tyler Chatwood is scheduled to start for the Cubs on Sunday, when the North Siders host the Brewers at 1:20 p.m. CT to conclude this three-game series at Wrigley Field. Righty Freddy Peralta is slated to start for Milwaukee. The game will be aired on Marquee Sports Network and MLB.TV.