"He's back, ready to work," Williams said of Harrell, who is currently in quarantine on the NBA campus in Lake Buena Vista, Florida. "Obviously Trez is a high-energy guy, he is a guy that plays at a high level, extremely physical player, extremely emotional player.
"With some things on his mind, I feel sorry for the other guys on the other team."
Harrell returned to the NBA bubble in the middle of the night Sunday. The Sixth Man of the Year finalist left the team on July 17 and recently lost his grandmother. Harrell has posted numerous messages on his social media accounts detailing how emotional the death of his grandmother was while also sharing messages about how motivated he is.
Harrell is one of three key Clippers who left the team briefly in July to tend to an excused family emergency. Patrick Beverley and Williams had also departed the bubble after losing loved ones.
Williams said he understands what Harrell is going through and he's ready for the Clippers to be whole again just before the start of the postseason.
"Obviously when Trez gets back, our group will be in full swing, our team will be in full swing," Williams said. "... I think you see us play well in spurts, then with the minutes and everything, I think our coaching staff, they're getting ready for the big picture.
"Mentally we're getting ready for the big picture. I know there's another level there. I know we have another place that we can tap into. I think guys are getting ready for that."
Clippers coach Doc Rivers said he's looking forward to the possible return of Harrell this week. Pending NBA testing protocol and clearance, Harrell could potentially come out of quarantine before the Clippers' regular-season finale against Oklahoma City on Friday.
"It would be kind of nice to have our normal rotation at least one time in the bubble," Rivers said when asked whether Harrell could be expected to play Friday. "We have to be the only team that has not had their normal rotation one game this entire bubble stretch. It's been tough in that way. But hopefully we can get it for one game."