There's a huge difference between "no" and "not now". The A's have never given up on Chris Carter; they have just said, after relatively small samples, "Not now," and returned him to AAA. To a lot of fans who wanted to see Carter get "a fair shake" a fair shake meant a large, uninterrupted sample at the big league level. But a player, not a team, dictates when a player is "ready for prime time," and it doesn't always take a very large sample to assess whether that time has come.
The key to Carter has always been "process," not results. The Carter we saw when he first came up is the same Carter we saw his second time up and in the Cactus League in March: A guy who approached each at bat like he was in trouble and who seemed to know, before the pitcher or fans did, that he was out.
The A's could have let Carter flail 300 times instead of 50 times, in order to look fans in the eye and say, "Hey we gave him a fair shake," but the major leagues are a "performance-based" level and if you want 300 chances sometimes you have to make more of your first 50. That doesn't mean you need to hit .250 or hit x number of HRs. What you need to do is to have enough quality at bats, show enough of an approach -- dare I go all "old school" on you and say "look like a hitter"?
Carter did the opposite. He forgot that when you're capable of hitting a "pitcher's pitch" over the RF wall with a free and easy, almost effortless, swing, that it's the pitcher who's in trouble every pitch, not you. And had the A's given him 300 at bats before now, he just would have failed more, for longer, which is bad for him and bad for the team. Instead the A's said, "Your time isn't now," reminded him of what he needed to do to succeed ("believe in yourself, attack the strike zone...") and stashed him safely back at AAA. They didn't release him, they didn't trade him, they didn't give up on him. They just waited.
And in his latest call-up, just 2 games and 8 PAs into this stint, Carter finally looks different. More relaxed, more confident, more in control of the at bats. Can he consistently recognize a good slider? We don't know yet. Can he turn on the inside pitch and still protect the outer half? Only time will tell. Is he finally ready to "seize the day" from the moment he gets here, and let his natural ability lead? Perhaps the answer is yes, and as a result perhaps he will finally get -- because he has finally earned, by showing that he is ready -- those 300 PAs to see what he can do over time.
I think the A's erred by wasting time trying to make a LFer out of a DH, and I think the A's would have been wise to give Carter more DH time to learn that "position" because it's probably where he'll end up if he makes it in the big leagues. On the defensive side, I would say Oakland has not played it all that well with Carter.
But in terms of giving Carter big league opportunities, and how long or short the leash has been? Players make their own opportunities, and not just through results but more importantly by process. Carter created his own small samples and now Carter may create his own "real shot". He leads; the A's just react. And that's exactly how it should be.