Well that week 1 game WAS against the Jets, and 2 of the games Roaf didn't play that LJ did (there was a 3rd that LJ didn't start but got the majority of snaps-Oakland), he went up against 2 lousy defenses in Buffalo ( ) and Houston. Welbourn missed another of LJ's starts, but there was no game that LJ started and in which he did well that both Roaf and Welbourn were both out. And Jordan Black, who filled-in for Roaf and Welbourn, according to snap.stats.com gave up 8 sacks last year in 10 starts, mostly at LT, but has a future at RT. He'll probably take-over there, but that still leaves a huge hole at LT and no one to fill it. Again this move blindsided the Chefs.
I think LJ is a great RB, but a great RB still needs a good O-line, and the Chefs suffered an enormous blow with the unexpected retirement of Roaf, if not Welbourn. Also Will Shields is getting up there as are Casey Wiegmann and Brian Waters (Shields will be 35 by the start of the season, Weigmann will be 33-1/2, and Waters is the youngster at 29-1/2).