I thought Christensen did a better job of helping Luck get rid of the ball quickly, relying more heavily on route combinations that had hot options, etc. This met with mixed results. Also, this very well could have been the game Arians' would have called; there's nothing in the gameplan that Arians didn't put there. The play calling was influenced, for sure, but this was Arians' gameplan.
What I hated, though, was the empty backfield on third down. Arians had been doing less of that over the past couple months, and again it's hard to tell what Arians would have done differently in certain situations. But I HATE empty backfield on third down, and we did it over and over again in this game, third and short, third and medium, third and long.
This offense, regardless of who is calling the plays, is still missing some crucial concepts that I think a good pro offense should have. For one, the offense relies on protection to be effective, and when protection breaks down, it asks the quarterback to make things happen. Our protection breaks down all the time, and the offense doesn't do most of the things that can take pressure off of the line and the quarterback, like including the backs in the passing game.
The route combinations feature concepts that stress a defense vertically and then underneath. (Unlike what people keep saying, the problem isn't that the receivers are always 20 yards downfield, it's that the underneath options rely on the deep routes to clear coverage. The underneath options are rarely primary options, they're most often crossing routes that still take time to develop.) This is a dangerous offense, as we've shown all season with big plays and lots of yardage. But it's not terribly efficient, and that's not just because we have a rookie quarterback and a bunch of rookie receivers. Roethlisberger has never been an efficient quarterback, even at his best. Philip Rivers' efficiency has deteriorated over the past two seasons, and before then, it relied heavily on big receivers making plays over defenders (very similar offense to ours). Both teams struggle to protect their quarterbacks.
Arians and his offense have a lot of positives. The team and fanbase should be exceedingly grateful that he was around this season, because he helped Luck and did a great job filling in while Pagano was out. But I don't think his offense is the long term answer for our team. I wouldn't be in favor of us getting rid of him, but given how strong he was as the top guy, I think he deserves a head coaching gig. And selfishly, since I think we need an offense that does more to stress efficiency, I hope he gets one.
I'm not necessarily disagreeing with anything you said here. I actually thought CC called a decent game yesterday-- not good or bad-- decent. And Luck's stat line was actually the best it has been in about a month with all of the short passes. But we didn't get a single TD. Winning is more important than Luck's completion percentage.
People have knocked BA all year long over the long pass plays. I just thought it was silly that now we are saying we need the long pass plays to be competitve when people were clamoring for shorter passes. That's all. I think BA has been beneficial for Luck this season, and I certainly would rather have BA than CC as the OC for Luck to have for the next few seasons. But I agree, there are better options than either out there. But like you said, BA isn't going anywhere unless he takes a HC position.
Regardless of who the OC is next year, fixing up this O-line in the offseason will make Luck and whatever offense we have much more efficient right off the bat.