The Phillies lineup has been in a five-week slump, their starting pitching is starting to show some cracks as they work with such little room for error, and Jake Arrieta is furious. Nothing to see here.

It sounds as though the Phillies are in great shape to begin their toughest stretch of the season — a four-week test that should indicate whether their strong start was just a mirage. The Phils open a three-game series on Tuesday against the Cubs at Wrigley Field. They will play 19 of their next 25 games against teams that would be in the playoffs if the season ended Monday; they won't face a team with a losing record until July 3.

Pass this test, and the Phillies would start July with a winning record and the likelihood of being buyers at the trade deadline. Struggle, and the attention would shift to which free agents they can court come winter and the countdown to the Eagles' training camp.

"We knew coming into this [10-game] road trip that this next month going forward was going to be a test. We're playing some good teams," Scott Kingery said after Sunday's 6-1 loss. "For us, we're going to have to step up. We have the ability to drive in runs. I know we're not stringing together hits and we're having some quick [at-bats]. It's not like what we did in the beginning of the season. We're in a little funk right now, but with the lineup we have, we can get out of that and start driving the ball more and start scoring some runs."

The Phillies enter Tuesday batting just .229 over their last 32 games, with a .303 on-base percentage and a .387 slugging percentage. In their last five series, they are averaging nearly four times as many strikeouts as walks.

Aaron Altherr has three hits in his last 30 at-bats, and his batting average has dipped to .181. Kingery had two hits in the series opener in San Francisco but then went hitless in the final two games, and his OPS dropped to a season-low .588. Maikel Franco is batting .200 in his last 50 at-bats, and Odubel Herrera is batting .167 over his last 54 at-bats.

Everyone is in a rut.

"I don't think were putting too much pressure on ourselves," Herrera said. "Right now we're going through a tough moment, but we're going to find a way to turn it around. It's part of baseball. It's disappointing."

They've walked only five times in their last 131 plate appearances, and that grinding approach they used early in the season to work deep counts is missing. The Phillies averaged just 3.67 pitches per plate appearance during their three-game sweep at the hands of Giants starters named Chris Stratton, Andrew Suarez, and Dereck Rodriguez. Manager Gabe Kapler said the Phillies need to get back to their "Philly style" at-bats.

"At-bats we were taking three weeks ago, where we were taking pitches, seeing pitches, fouling off pitches, working deeper counts and putting the ball in play," Kapler said. "We need to get back to working deep counts."

Zach Eflin will start Tuesday night against the Cubs in an outing that could decide his future in the rotation. Enyel De Los Santos and Cole Irvin are pushing for promotions at triple A.

The starting rotation carried the Phillies through May, while the lineup struggled. But Eflin has since faltered. Nick Pivetta lasted just four innings in his last start,and Vince Velasquez is 0-2 in his last three starts, despite posting a 2.20 ERA in that stretch.

It was easy to understand why Arrieta was so frustrated on Sunday that the team scored just one run — and he was the one who drove it in. The offense has given the rotation little support. There was no reward for their great month of May.

The rotation's ability to hold the team afloat might well determine whether the Phillies pass this crucial test. In four weeks, the Phils will have a better idea whether everything is fine.

"It's a good opportunity for our young team to show some resilience and bounce back and be much stronger in the series in Chicago," Kapler said. "It's an opportunity to learn from some of the mistakes we made in the [San Francisco] series and make some adjustments. Much like we bounced back from the [5-4] loss to the Nationals" in Washington on May 6, "I think we can put this one behind us."