But Williams does have a target date in mind. The Nats manager would like to see Harper back by July 1.
"He's continuing to work with the therapist and do a little bit of strengthening, but he can't swing a bat yet, it's not time yet," Williams said. "He's itching, he's pacing. But that's one of those things where he's 21 years old and if it doesn't heal right, it can affect him long-term. So we want to make sure he's good before he's able to get back out here.
"So we don't know yet (when he'll be back). I'd like to see him back by the first of July. I think that would be a good target, but we just don't know. It depends on how everything else goes."
Harper was out on the field Tuesday, fielding grounders and making some throws just to maintain as much motion as he can and maintain some level of baseball activity without doing too much.
"He's progressing. It's a slow process," Williams said. "(Ryan Zimmerman's) different. When the bone's healed, the bone's healed. But with this one, it's a lot different."
Williams went into greater detail about how the recovery for Harper's torn ligament is a longer process when compared to Zimmerman's fracture.
"He'll be a little bit longer time off as well, and he won't be able to do as much defensively (as Zimmerman)," Williams said. "So that'll take him a little bit longer to get him back in shape. He's lifting. He's doing all his leg stuff and running and all of that, but he won't be able to do as much baseball activity as Zim was able to do. So it may take a little bit longer."
Williams also provided an update on left-hander Gio Gonzalez, who is out with shoulder inflammation. Gonzalez remains on track to make a rehab start for Single-A Potomac on Friday.
Gonzalez threw 35 pitches during a bullpen session Wednesday and is scheduled to pitch four innings and 60-65 pitches Friday. Williams said if Gonzalez gets to five innings within the frame of that pitch count, the Nats will allow it, but five innings will be the max.
"He's good to go. He'll go Friday," Williams said.
Gonzalez's return will strengthen a rotation that is performing at a supremely high level of late. Nats starters have held opponents to three earned runs in 27 innings over the last four games for a sparkling 1.00 ERA during that time.
Williams is pleased with what he's seeing from the rotation right now.
"I think that even the first couple of months, I think there were high expectations certainly, but I think they've kept us in games and given us a chance," Williams said. "The last turn around, the rotation's been pretty special. We certainly can't expect eight innings of shutout ball every night. It's not going to happen, but they've been really good. They'll just continue to work hard and do that."
Speaking of quality pitching, how good has reliever Tyler Clippard been over the last seven-plus weeks?
Since his ERA sat at 5.40 on April 11, the Nats' eighth-inning specialist hasn't allowed an earned run. Not one.
Clippard has pitched 18 2/3 innings over 21 straight appearances without permitting an earned run, lowering his season ERA to 1.42.
Williams said control of one pitch above all has made the difference.
"I think for the most part, it's been his changeup command and being able to throw that in any count during an at-bat for a strike," Williams said. "That opens everything up for him. That opens up his high heater, it opens up his curveball and his split, and every other pitch that he wants to throw. So for me, that's what he didn't really have early. He got behind, was not able to throw the changeup for a strike and that was the difference. So he's had that and he's pitched really well."