Julian Edelman, Dion Lewis

New England Patriots running back Dion Lewis (33) congratulates wide receiver Julian Edelman (11) on his touchdown in the second half of an NFL football game against the Miami Dolphins, Thursday, Oct. 29, 2015, in Foxborough, Mass. (AP Photo/Steven Senne)

(Steven Senne)

Throughout the summer, Dion Lewis was a ghost, the lone player on the PUP list not to make an appearance on the Patriots practice field.

Lewis was recovering from ACL surgery and, as we learned in late August, required a second procedure on his left knee.

With his potential return nearing, reporters have frequently seen Lewis in the Patriots locker room -- he strolled through Wednesday without a limp and without a brace on his knee -- but we still have limited details on the nature of his surgery and the status of the knee.

So here's what we know:

Lewis, the electrifying tailback who burst onto the scene a year ago, is currently on the PUP list. He is eligible to practice as early as next week, but it remains to be seen if he is healthy enough to practice.

Per PUP rules...

The earliest Lewis can return to practice: Monday, October 17

The latest Lewis can begin practicing: Tuesday, November 22

The earliest Lewis can make his 2016 debut: Week 7 versus Pittsburgh

The latest Lewis can make his 2016 debut: Week 14 versus Baltimore

Once a PUP player begins practicing, he can remain on the PUP list for a period not exceeding 21 calendar days. So if Lewis practices on Nov. 22, the latest he can be activated is Monday, December 12, when the Pats host the Ravens on Monday Night Football.

As steady as James White has been, Lewis obviously adds a new dimension to the Patriots offense, which already has a nice stable of playmakers in Rob Gronkowski, Julian Edelman, Martellus Bennett, White, Chris Hogan, and Danny Amendola.

As we saw with Gronkowski's hamstring issue, the Patriots will be patient in bringing back injured players, especially if they continue to cruise through the regular season.

While it's impossible to predict injuries, the Pats want to give themselves the best chance to be healthy heading into the playoffs. They certainly do not want a repeat of 2015, when the league's best team was wrecked by injuries late in the year.

For this reason, it wouldn't be a surprise to see the Patriots proceed cautiously with Lewis.