PHILADELPHIA -- Zack Wheeler appeared to be in fine spirits Tuesday evening before Game 3 of the World Series.

But how is his right arm feeling?

Wheeler is experiencing arm fatigue, according to the Phillies. It is why, they said, he will remain their Game 6 starter, despite Game 3 being postponed from Monday to Tuesday due to rain. The Phils could have moved up Wheeler to pitch Game 5 on Thursday on regular rest. Instead, he will get a sixth day of rest before Game 6, if necessary, on Saturday in Houston. Philadelphia thinks Wheeler needs it. His fastball velocity dropped from an average of 97 mph in his first four postseason starts to 95.2 mph in Game 2 last Saturday at Minute Maid Park, where he allowed five runs in five innings.

His fastball averaged 95.8 mph in the regular season.

“I’m really confident he'll be ready to go,” Phillies manager Rob Thomson said.

Wheeler was unavailable to comment on Tuesday, but Thomson offered his opinion on why Wheeler struggled in Game 2. Wheeler missed a month late in the season because of tendinitis in his right forearm, although the Phillies have been careful with him since he returned. He has not thrown more than 96 pitches since he returned from the injured list, including the postseason.

“So when he went on the IL, we brought him back, and not that we rushed him, but we ramped him up pretty quick,” Thomson said. “And I think that took its toll on him a little bit, and I think that's why you're seeing now the velocity go down a little bit. So I'm hoping the extra couple days will help him.”

Phillies president of baseball operations Dave Dombrowski also feels like the extra day could help Wheeler.

“I think [at this time of year], if you’re tired, if you get extra rest, it could help you,” he said. “We’ll see.”

Asked if Wheeler received an MRI exam, Dombrowski said, “He’s in a situation where he feels good and he’s ready to go. That’s the way it is. You know I can’t disclose that type of information. That’s all HIPAA stuff.

“He’s not injured.”

If Wheeler’s velocity does not jump back up, he will have to pitch with what he has. It can be done, of course. It will just be a greater challenge against a talented Astros lineup.

“I think there's probably a lot of conversations with the trainers and strength and conditioning and trying to figure out, ‘OK, how do we adjust my program, what did I do differently, maybe?’” Thomson said. “And I think there is a part of it where you have to think about, ‘OK, if I don't have my velocity, what am I going to do? Am I going to lean more on my slider or my curveball or my changeup?’ Really focus on commanding the ball. You got to figure it out if you don't have your best velocity.”

Wheeler will throw his bullpen session Thursday before Game 5.