It seems to me like many people have been eager for there to be another point guard controversy and have had a strong tendency to see way more in Jack than he's actually shown. Even back in preseason, when both the guards were struggling, this site would harp on Calderon's poor play while mostly ignoring how terribly Jack was running the offense. (It really was terrible -- it was scoring less than 90 points per 100 possessions). And he really was astonishingly terrible in the preseason and first 10 or so games of the season, shooting as badly as wright, turning the ball over a ton, and totally failing to run the offense.
Even when Calderon was struggling, he still facilitated the offense, which Jack didn't.
Jack has gotten a pass for all his bad play, and as soon as he has a few good games, a chorus of voices anoints him the new starter. I really don't get where this is coming from. He's a good, solid player, but he makes careless turnovers and his court vision is not on Calderon's level.
Last year, the year where Calderon was hampered by injury? He still produced at an amazingly high level. His offensive production was ridiculous! People don't seem realise the amazing contribution Calderon makes to the team's offense. Last year, his offensive rating was 123. By comparison, Kobe's was 115 and Chris Paul's was 124.
Now, his defensive rating was 112 and CP4's was 103. So yes, he gives away something on defense. But when Calderon is playing at his usual level, you gain way, way, way more on offense than you lose on defense. Like, it's not at all close. 11 points difference between offensive and defensive ratings is a big deal.
Now, Calderon has played worse this season, and he's been injured again. But if Jack gets a pass for his terrible start, then so does Calderon. Calderon at least has the excuse that he didn't play all summer due to recuperating his injury -- what was Jack's excuse? Don't get me wrong, I'm not slagging Jack, but the fact is that Calderon has still outplayed Jack this year, even though he's played well below the level he's capable of. The stats certainly back this up, and so does my impression watching the games. I'm not too impressed by the claims that people are 'more comfortable' with Jack running the offense, because it has been obvious since the beginning of the season that plenty of observers on this site have been eager to see more in Jack than is there.
Now, if Jose never regains his form of the last 3 years, whether he or Jack is better might be a debate. But Jose had already started to play back to his old level before the injury. And if both Jose and Jack play at the level they're capable of, we'll have a not-quite all-star and a borderline starter (that is, someone who can start, but will generally be worse than whoever is starting for the other team) at the point guard spot. That's great! But let's stop forgetting what Jose has consistently given us for 3 years and overrating a good but not great player in Jack.
For verification of their relative contributions, see