Since Mankins is practicing, it means that he has been activated off the PUP list. Mankins was held out of the first three weeks of training camp due to offseason knee surgery to repair a torn ACL. It was an injury that he suffered late in the 2011 season, and played through the playoffs with.
While his rehab wasn't expected to keep out of the entire season, it wasn't known whether or not it would cause him to miss the start of the regular season. Since a player isn't allowed to practice and then be placed on the reserve/PUP list, this is a sign that the Patriots likely think Mankins will be ready to go for week one.
More analysis after the jump!
Mankins' return comes at a bit of a desperate time for the Patriots, with the offensive line performing sub-par against the Saints this past Thursday. Donald Thomas and Ryan Wendell had been playing in Mankins' place. With Mankins back at his usual left guard spot, the Patriots offensive line immediately has more flexibility. Should Brian Waters not return, the Patriots will have the option to start veteran Dan Koppen at center, and Dan Connolly at right guard. A Mankins-Koppen-Connolly interior line isn't as good as one that has Brian Waters in it, but it's certainly solid.
Having Mankins back is great news, and certainly provides some kind of relief to the depth and experience issues the Patriots have had on the line. Still, there are a lot of unknown questions on the offensive line, mainly concerning the absences of Brian Waters (Did Not Report) and Sebastian Vollmer (back).