Let's see: Mannelly played in the NFL and was the best at his position for almost 20 years. He played with Lance Briggs for Lance's entire career (11 year or so?). He played on the team with Lance as recently as 9 months ago. He thinks it's an issue.
I've also heard Hall of Famer Michael Irvin say it's an issue. I also heard very astute NFL analyst and former defensive player Matt Bowen say it's an issue.
So, I defer to those guys. If they say it's an issue, it's an issue. It can be argued as to how big of an issue, but I defer to them.
To me it's simple. The final roster of defensive players (who have spent very little time together in the preseason) was finalized on Saturday. If the Bears have the opportunity to have 5 practices (on field, the room, etc) then I would prefer to have the entire group there so they can gel as a unit. I'd expect their veteran leader to be part of that session. Lance not being there is probably not that big of a deal, but for the way this D played last year, I would expect them to be there OVERTIME, not taking time off.
Just poor timing. Lance had 5 months off to open the restaurant. He also has a bye week that will come quickly. That would have been the right time.