The right-hander is still dealing with inflammation in his right elbow.
"It's feeling better and I'm sure if this was a playoff game, he'd say, 'Give me the ball,'" manager Rob Thomson said before Friday night's game against the San Francisco Giants.
"But he's still feeling it a little bit so we're going to wait and re-evaluate on Monday or Tuesday."
Wheeler went on the injured list last week with what was termed forearm tendinitis. He wanted to pitch through the issue but acquiesced to the team's wish to follow a common-sense path and take a break. It was supposed to be a quick trip to the IL with the pitcher missing just two starts. But Wheeler played catch to 90 feet in Arizona on Wednesday and still felt some discomfort, according to Thomson. The team sent him for an MRI in San Francisco on Thursday.
"There's nothing," Thomson said. "No structural (issues). Just a little bit of inflammation in the elbow. We'll back him off and wait till that gets out of there and he's comfortable then we'll go."
Wheeler will not throw a bullpen session this weekend in San Francisco, as had been planned. The pitcher did not make himself available for comment, so it was not known if he agreed with this latest slowdown or not.
The loss of Wheeler has come as the Phillies are trying to run down their first playoff berth since 2011. The Phils entered Friday night in control of the second NL wild-card spot with 30 games to play, but a healthy and effective Wheeler is crucial to the team's nailing down a playoff berth.
Thomson was asked what his level of concern was on Wheeler.
"None, really," he said, citing Thursday's MRI.
Time will tell where this goes. In the meantime, Bailey Falter will remain in the rotation. He's made two starts with Wheeler out and won both. Aaron Nola lines up to pitch Tuesday at home with Falter sliding in on Wednesday. The Phils play Miami in both of those games.
Two potential stretch-drive bullpen arms were in action Friday.
Zach Eflin threw 35 pitches in the bullpen in San Francisco and said he felt "awesome."
Eflin last started on June 25. He's been out since with soreness in his surgically repaired right knee. There's hope he can continue to progress and possibly help out of the bullpen in the final weeks of the season. He will throw another bullpen session in the coming days before possibly getting some innings in the minors.
Back East, rifle-armed right-hander Griff McGarry, usually a starter, got two innings of work out of the bullpen for Double A Reading. He did not allow a hit, walked one and struck out four. His fastball reached 99 mph.
Thomson said the team wanted to get a look at McGarry in a relief role to gauge if he could be an option for the big club.
"We're a little bit thin," Thomson said. "He's got a big arm."
The bullpen is missing Seranthony Dominguez, who has been out for two weeks with right triceps tendinitis. He is feeling better and will test the arm in a bullpen session Saturday in San Francisco. The Phillies hope to have Dominguez healthy and firing for the final weeks of the season. He first would have to get some work in the minors.