Two things the San Francisco 49ers proved by coming to terms with the famously flawed David Carr on Sunday evening:

First, Patrick Willis does not have Twitter veto power on roster decisions, though maybe he should.
Second, good and loyal soldiers such as Shaun Hill are not always treated kindly.
Oh, yes, the 49ers raised many questions by even trying to sign Carr, presumably and primarily as a way to replace Hill as the backup and perhaps to challenge Alex Smith.
Willis, possibly speaking for many in the locker room, declared on his Twitter account that he thought the 49ers already had three quarterbacks better than Carr, including Nate Davis.
The 49ers’ management did not agree, however. (Willis has since said that he will gladly accept Carr as a teammate. But Willis did not renounce his original opinion—and good for him.)
And now that they have come to terms on a two-year deal with Carr, the 2002 No. 1 overall pick instantly becomes the flash point to larger questions: What are the 49ers doing at quarterback, and what makes them think Carr is a partial solution?
They can’t duck it: The 49ers have opened themselves to the scrutiny.
They’re the ones who lauded Hill’s leadership and game-management skills seven months ago, then declared that Smith was a natural long-term starter.
So what do they do? Woo and land Carr, who has all the tools but, so far, none of the NFL success or true grit.
If Hill is out, does that mean the 49ers have new questions about Smith’s status, too? Is locker-room chemistry not that important any more?
If Carr is in, does that mean they’re not interested in acquiring a more legitimate quarterback—such as Philadelphia’s Donovan McNabb?
All these issues, all raised by the signing of Carr, a 30-year-old who hasn’t been a regular starter since 2006 and who has an NFL record of 23-56.
And who has been sacked a staggering 265 times, which is enough to shell shock five or six quarterbacks.
Hey, maybe general manager Scot McCloughan, coach Mike Singletary and offensive coordinator Jimmy Raye had it all plotted out this way from January.
Maybe they long ago decided that Hill—who beat out Smith to open the 2009 season, then lost the gig in Game 6 — was no longer necessary.
Maybe they figured their first personnel move of the spring must be to upgrade the backup spot.
It’s entirely possible that the 49ers’ brain trust believes Carr and Smith will have a strong natural competition, which will only make the team better.
I don’t know about that, however. Smith has lost training-camp battles in 2005 (to Tim Rattay his rookie season), 2008 (to J.T. O’Sullivan in the Mike Martz year) and last year to Hill.
Smith just doesn’t seem to thrive in the training-camp atmosphere when his job is on the line.
Maybe the 49ers thought Smith and Hill were too close and couldn’t generate the kind of tension that might lift each other higher.
But there is a small problem with that line of thinking, which was at the heart of Willis’ point, I believe.
When precisely has Carr proved he is better than Hill or worthy of taking on Smith?
While he was losing game after game for five seasons in Houston? While he was holding a clipboard in Carolina and New York the past three seasons?
It would not be out of hand for the 49ers to have questions about Smith, of course. And it was not wrong for them to bench Hill in the middle of last season.
They have assembled a lot of receiving weapons, and they obviously want to make sure they have a quarterback who can deliver the ball to them.
But if Smith can’t hold off Carr to keep his job, then that does not speak well for Smith. The 49ers will be in trouble.
And if Carr ends up as their starting quarterback at any point, his track record tells us that the 49ers will be in trouble, no matter what.
What are the 49ers doing at quarterback? I don’t know. I can’t tell. I’m not sure many of the players in their locker room can tell, either.