Patriots have critical issue at left guard

In general, the New England Patriots have stability on their offensive line.

They seem set with left tackle Matt Light, center Dan Koppen, right guard Stephen Neal and right tackle Sebastian Vollmer.

But a line is only as strong as its weakest link.

Left guard is busted.

The Patriots have a fractured relationship with unsigned Pro Bowl guard Logan Mankins. He is not in camp and has demanded a trade.

ESPNBoston.com's Mike Reiss reported Friday that Mankins' projected replacement, converted tackle Nick Kaczur, will be out indefinitely with a back injury that could wipe out his entire season.

That puts Dan Connolly, with four starts in his five-year career, on the first unit.

Reiss wrote an analysis of the Patriots' offensive line, noting the Patriots have had no contact with the Mankins camp since he went public with his trade request.

Mankins is a smash-mouth player, and one of the Patriots' priorities for 2010 is to become more physical.

"At this point, we're doing what we have to do," Light said. "We have a lot of guys who are stepping up and playing well. Then again, you can't make up for a guy who is a Pro Bowl player and has had as much experience, as many games, as many snaps as Logan has. Outside of that, everything is going well."