I think it's mostly inexperience. Another huge factor is instability.
They got off on the wrong foot last year when their wide open passing game crashed, their defense started slowly, and their running game was puny. And there were clear reasons for all of it. Saffold gets hurt right off the bat, so we get no push in the running game, and they hadn't figured out that Stacy was the best RB we had yet. We were getting gouged in our run defense and the loss of Dunbar and the inexperience of Ogletree hurt big time and that Walton was in way over his head as a DC. Too much pressure was put on the passing game and the WRs just weren't good enough to make Bradford's job easier. Then by the time we get the running game going, Bradford goes down. And it was after Bradford went down that the defense FINALLY put it together especially on the run defense. Remember how the Texans just tore up our run D?
I believe there's a good chance that we start out where we left off on defense last year and actually it should be much better with GWilliams running the show and the influx of talent with Donald and the rookie DBs. This has got to make Bradford's job a lot easier than what he had to face last year as far as having good field position and multiple opportunities versus playing from behind. Then toss in the power running game with Stacy and Mason running behind Saffold and the Big G, and Bradford's job gets even easier. It should be comparable to what Russell Wilson had last year only the Rams OL is better and so are the Rams WRs.
Really what I think it will come down to is Bradford's performance. If he's as good as Wilson we should go to the Super Bowl. If he's as good as Alex Smith we should make the playoffs. Neither of those guys had a solid receiving corp but they got the job done with good D and a solid running game.
It's gonna be very interesting to see how it goes for SB this year if the D plays great and the running game is solid. Bailey and Austin are quality weapons. They are as good or better than anything the Seahawks had last year. Add Quick, Givens, and Britt to the mix and should one of them emerge then we've got a solid WR corps; More than enough for SB to get the job done. And clearly our STs are top notch, good as any in the NFL. If the WRs are decent, and the D and running game go as expected then it will all fall on Bradford's shoulders. Everybody knows it, but no one knows if Bradford will get it done.