What the center fielder, recovering from core muscle surgery, has experienced is a growing comfort on the field during a rehab assignment with Double-A Harrisburg.
While Williams admitted Span was "a touch tentative" in his first few games, he lately has improved making plays -- including a shoestring catch and an attempted stolen base -- without hesitation or consequence.
"Any time you have an injury and you have to come back from it, it's important to get in the flow of the game and not think about it, just react as a baseball player, and he's at that point now," Williams said. "Just go do it, and he doesn't have to think about it."
Span, 31, batted .302 last season in 147 games, with a .771 OPS and a National League-best 184 hits. He had surgery on his right core muscle on March 9. He had the same surgery on his left side in December.
"All our guys are watching him every day and giving those evaluations to us," Williams said. "The ultimate is him, how does he feel?"
The Nationals should have a better idea in the next couple of days.
Span played seven innings Thursday, going 3-for-4 with a home run. He is scheduled to play nine innings on Friday, but Williams said, "We'll see how he wakes up." A possible day off Saturday would be followed by an evaluation of how Span's body reacts.
"We'll evaluate at that point what we're going to do next," Williams said.
It is clear, though, that the process has accelerated.
"Those are the things we're looking for from him, in that he can react on the baseball field and not have to go, 'OK, the ball is hit, let me think about this,' and then go after it," Williams said. "He just goes. I think he's at that point now."