Absolutely. Agreed about JJ > Amir individually at PF + better fit alongside rest of starting unit.
Well you've always had a soft spot for JJ, still JJ has been terrible so far this season.
I'll also point out that we've been pretty good to start games, so...
Let's also point out that so far our real only struggle is rebounding... and Jerebko so far has been our worst rebounder other than Brown.
But if you want to move away from Amir, why not try Zeller over Jerebko? Not my preference, but still more deserving.
I'd also try Brown at SF, who's already playing in crunch time with our starters as it is, before trying Jerebko. Sucks rebounding, but is doing a lot of good stuff out there.
I'd also try Jordan Mickey at PF, who's one of our best rebounders, prior to defaulting into Jerebko...
Would Jerebko play better with our starters? Sure, but that should be true just about anyone, sadly his performance says that he should be eating the bench rather than being promoted to the starters.
1) Outisde of ORB%, which is easily explained by the differing games of Amir and JJ - JJ can shoot and Amir can't, JJ's rebounding percentages are pretty close to Amir's percentages. Further, once again, moving Horford closer to the basket will only increase his rebounding percentages and bring them more in line with his career percentages and what we saw in preseason. He's been forced to be more out on the perimeter due to Amir's deficiencies.
2) Zeller doesn't help any of the things I mentioned, because he's a pure center. He's probably worse than Amir defensively, and though he might provide a bit more spacing than Amir, he still clogs the lane and forces Horford out on the perimeter.
3) It's a joke to consider Brown as a starter with this lineup. That'd make us nearly a historically small-team, would kill our rebounding even more, and would put a rookie in the starting lineup guarding the Lebron's, Melo's, and KD's of the world when he's been pretty terrible with his perimeter defense already.
4) The same thing can be said about Mickey. It's funny that you're making fun of the idea of playing JJ more when you're advocating for playing Mickey, who can barely even get trash minutes for us.
It's convenient that you ignore how well JJ played with the actual starters in this whole conversation, and it's even more convenient that you ignore that this move goes way beyond the individual play of JJ. In fact, it has just as much, if not more, to do with the benefits outside of JJ's individual game as it does with his individual game.
I haven't ignored anything, I'm just not letting myself get swayed by a factor that holds true with just about everyone in the team, or one playoff series last season over current performance.
When Jerebko starts playing better, and better than his other teammates, come back at me.
Oh, you're not being swayed by the evidence that goes against the narrative you're pushing and is the very thing that I'm arguing? Hmm, I wonder why that is...
Come back at me when you have an actual argument with substance other than JJ not playing well in the first three games of the season. 
It's clear that JJ is a much better fit next to Horford than Amir, whose offense is virtually non-existent at this point, and I've been beating that drum since this summer. Amir was a good fit for us last year as a starter, but he's not an ideal fit next to Horford. He'd be an excellent back-up big for us, but he's not starting material with us with Horford now.
I'm not painting a narrative other than Jerebko has been quite bad, and has been so since preaseason as well, this season. But for you this season so far is important as long as we don't measure Jerebko by it.
I'll elaborate now a bit now that I have time.
You're claiming "Amir whose offense is virtually non-existent at this point", but the same can be said by Jerebko. He could come out of that slump, but as you said... at this point... it's been non-existent as well, and worse than Amir's at that.
For more reference: Jerebko has the lowest PER currently on the team, 2nd worst TS%, 2nd worst Rebound %, the only player with a negative win share so far on our team, and the worst FG% of our team so far this season. Most if not all of these woes were also present during the preseason. By far he's been our worst offensive player this season, hope that changes, but based on his play so far I wonder if he even deserves playing time.
You alluded to a decreased rebounding from Horford as a potential reason for our poor rebounding, and that playing him at center might solve that. What it also ignores is that Amir is currently 4th in rebound percentage, and as mentioned above Jerebko is next to last. So I don't think a slightly improved Horford rebounding would make up for the gap that currently exists between Amir and Jerebko, again currently.
Keeping that in mind is why I suggested Zeller as a potential. Don't like his defense, but he could fit well with the starters (as seemingly anyone would), plus he's currently our leading rebounder. Not my first choice, but it could address that problem in some way, based on current play.
As for Brown, well he's a actually [dang] good sized for a SF and Crowder can easily move to PF there. I don't see the problem, it's a unit we've been using in the fourth quarter as it is. Brown is playing quite well. Only issue is that he's been a very poor rebounder, but as mentioned Jerebko hasn't been rebounding that much better as it is, but Brown has been exponentially better than Jerebko offensively. Plus he's another player who can create shot opportunities.
As for Mickey, I think Stevens is making a big mistake keeping him on the bench. He was one of our best performers in preseason. He one of our best rebounders and defenders, plus it addresses your problem of having to play Horford at PF.
And once taken into consideration how poorly Jerebko has been playing so far, any of the candidates above would probably get my vote.
But honestly I don't care either way, start Jerebko over Amir, whatever. I just find the notion of giving our worst peformer so far this season a starting job a bit repulsive in the face of it when in many ways I think he should be eating the bench fully right now until he can show otherwise once again.
In the end, we need to see more games... 3 games when our team is playing well, our first unit is playing well, seems like a poor reason to mess with it particularly to, once again, insert our worst performer so far.