When Bryce Harper ran onto the field a few minutes past 7 p.m. Tuesday, he thought the Phillies had picked up innings-eating left-hander Tyler Anderson in a trade with the Pittsburgh Pirates.

“They said we acquired him,” Harper said three hours later, after the Phillies’ 6-4 loss to the Washington Nationals, “and he should be here tomorrow, right?”

Uh, not so fast.

Although the teams agreed to the trade at about 4 p.m. Tuesday pending a review of medical information, according to multiple sources, the Pirates raised concerns about the health of 20-year-old right-hander Cristian Hernandez, one of two single-A players they would have received. Once the deal stalled, the Pirates decided instead to send Anderson to the Seattle Mariners for two minor leaguers in a trade that was announced after midnight.

And so, with the trade deadline looming at 4 p.m. Friday, it’s back to the drawing board for the pitching-strapped Phillies, who are in dire need of rotation help with Zach Eflin’s injured right knee progressing more slowly than expected.

Phillies officials were unavailable for comment late Tuesday night.

» READ MORE: Matt Moore’s rough night shows Phillies need more than just one new starter and other observations from a 6-4 loss to the Nationals

Anderson, 31, is eligible for free agency after the season. If the Phillies decide to pursue other rent-a-starters, they could turn their attention to the Colorado Rockies’ Jon Gray or the Chicago Cubs’ Zach Davies, both of whom may be available at similar acquisition costs to Anderson.

The Phillies were poised to send Hernandez and 21-year-old catcher Abrahan Gutierrez to the Pirates. According to a rival scout who watched both players at single-A Clearwater, Hernandez projects as a back-end starter, while Gutierrez has the raw tools to perhaps be a backup catcher in the big leagues.

It’s not yet known if the Phillies offered to replace Hernandez in the deal. Perhaps it’s coincidental, but there’s history between Pirates general manager Ben Cherington and Phillies president of baseball operations Dave Dombrowski. Cherington resigned as GM of the Boston Red Sox in 2015 after they hired Dombrowski to replace him as the top front-office decision-maker.

The Phillies’ attraction to Anderson was his consistency. He has a 4.35 ERA in 18 starts for the Pirates (league average for NL starters is 4.01), but has gone at least five innings in every start and worked 103⅓ innings overall. The Phillies haven’t been able to count on five innings from Vince Velasquez, Matt Moore, or Spencer Howard, the primary occupants of the No. 4 and 5 spots in the rotation.

The Phillies are hunting for help for the rotation and bullpen. It appears they intensified their search for starting pitching in recent days, especially with increasing uncertainty about Eflin’s knee injury .

And their rotation needs were amplified after Velasquez lasted only 2⅓ innings Friday night, Howard bowed out in the fourth inning Monday night because of a callus on his right hand, and Moore gave up six runs in the first two innings Tuesday night.

“It’s very tough as an offense to come out each night and try to score six, seven, eight runs,” Harper said. “It’s just not possible, especially with the pitching in this division and this league.”

Anderson was scratched from his scheduled start Tuesday night against the Milwaukee Brewers, the first sign that a deal may be imminent. The Phillies were hoping he could make his debut for them Thursday against the Nationals at Citizens Bank Park. Now, it appears they will have to go with Velasquez, as scheduled.

» READ MORE: Zach Eflin will miss at least one more start with lingering knee injury

Eflin has missed his last two starts after going on the injured list with patellar tendinitis in his right knee. He threw a bullpen session Sunday, and manager Joe Girardi said Monday that Eflin is “not quite where we need him to be.” Girardi didn’t have an update Tuesday, and Eflin has not been available for comment.

The Phillies’ best chance to win a weaker-than-expected NL East rests with quality innings from top-of-the-rotation starters Zack Wheeler, Aaron Nola, and Eflin. They were among only four teams that had three starters with at least 100 innings in the first half of the season.

“If you’re going to go on a winning streak, which you need to do at some point to win [the division], that usually means you have good starting pitching,” Dombrowski said over the weekend. “That means we need Aaron and Zach Eflin to pitch well. And I think they’re capable. If they’re pitching up to their capabilities, I think our fours and fives can get by with five innings with a deep bullpen. Because, really, most fives, that’s what they’re doing now today.”

Regardless of what happens in their starter pursuit, the Phillies are expected to continue looking for bullpen help before Friday’s deadline.

Cubs closer Craig Kimbrel is the marquee name on the reliever market, but the acquisition cost is expected to be prohibitive. The Rangers are likely to move Ian Kennedy. Pirates closer Richard Rodríguez, also expected to be dealt by Friday, is another possibility, although it’s not clear whether the Phillies would attempt another deal with Pittsburgh.

The Phillies lead the league with 25 blown saves, so their search for bullpen help isn’t limited to closers. They are investigating setup men, including the Cubs’ Ryan Tepera, the Rockies’ Mychal Givens, and Twins lefty Taylor Rogers, who went on the injured list this week.