Any weakness along the OLine will be attacked in particular, but if the O Line has an ability to work together (with help), it can offset any weakness. Thus, good unit play can mitigate the loss of a spectacular starter.
To make my case in point, Jonathan Goodwin (who enjoyed ProBowl and Madden Most Valuable Protections Award status while with the Saints) did not make the Pro Football Focus rankings as 49er. And has, in fact, been less than stellar the past season.
The season will tell us whether the Saints were able to accurately assess Ben Grubb’s abilities or integrate him in the Saints system. However, the unit’s past success and Drew Brees’ quickness bodes well for the upcoming season.