I think Jones would win 2 out of 3. Calzaghe's workrate, unorthodoxness and chin always keep a close fight, but in the end, i think Jones' speed would edge Calzaghe's strengths. Calzaghe has the right style for Jones though, and there are not many 168'ers who i would give a better chance than Calzaghe.
Against whom though? Throwing 100 punches a round against truck drivers and throwing 100 a round against Calzaghe are two completely different things. Kessler also threw 80+ punches a round against lesser fighters. What happened when he fought Calzaghe? He averaged far less because he was taken out of his comfort zone and so would Jones be. Calzaghe is a rythem-break fighter with his unorthodox style. Incidentally, you thought Calzaghe had no advantage against Kessler either but he won anyway (and pretty convincingly, i might add).
How many punches per round did Calzaghe throw vs Starie, who fought defensively most of the time? Where he disappointed the Showtime so that it abandoned the idea of making him fight in US. Calzaghe has zero chance of breaking a rhythm of a fighter who has no set-up rhythm in the first place, fighting according to situation, not repeating himself, and with a style far more unorthodox than Calzaghe could dream of.
Calzaghe would be fighting a superior mirror image, not a good recipe for success. If you want to argue in Calzaghe's favor, I guess you could say that Hopkins was able to win four rounds thanks to aggressive movement of his feet. However, Bernard always has been (even then) a better defensive fighter than Calzaghe, and that version of Hopkins was very fast as well. Anyway, Jones matured and gained a lot moving from 160 to 168, and at that weight he'd have to be a clear favorite over Joe. The difference in power is dramatic, and those occasions when Calzaghe falls in and gets square would be a big problem. He isn't going to attack Jones and find a stationary target, as he did against both Kessler and (especially) Lacy. I love Calzaghe and celebrate him as a great, but prime Jones wins by at least 8-4, and possibly gets a late stoppage.
People talk how Calzaghe adjusted his tactics in the 4th (?) round. Compare that to 168lb Jones adjusting all the time to the situation in the ring. He was all the time varying his actions. Footwork - moving forward, backward or circling, in and out or flat-footed, sidestepping and circling around the opponent till he's literally behind his back. Counter-punching, jabbing, flurrying, rope-a-doping, slugging it out, varying light and heavy punches or mixing both kinds together in combinations, leading with jab, leading with left hook, with straight right, left or right hooks to the body or to the head, throwing single punches or combinations. Doubling, trippling or even quadrupling jabs or hooks. Changing stances, sometimes fighting almost full round as a southpaw, as effectively as he was fighting in orthodox stance. Changing tempo and punchrate, changing angles, keeping hands low or raising them up and moving forward behind high guard, pushing the opponent backwards. Blocking, parrying, slipping, ducking, rolling with punches, stepping back or side-stepping or closing the distance into a clinch. And he was varying all these things all the time at 168lb, you could never guess what he'd be doing in a few seconds from now.
I agree with most of your post, but when did Roy ever slug it out? He allowed plenty of inferior fighters to bang at him some on the ropes, but I can't remember him ever engaging in a trade situation in the middle of the ring.
I've asserted in an earlier post elsewhere that Calzaghe is a Ring General. His style combines sound technique with unorthodoxy, and he forces you to keep up with a what seems like a crazy crackhead dance but is actually an exploitation of everything you do and think. That being said, Jones would knock him out at SMW. Calzaghe would not be able to spoil Jones's boxing. The reason is interesting. Jones, in my well-documented estimation, does not have sound fundamentals. He is an athletic phenomenon with speed, power, timing, & good placement. However, Jones is a too much of an unorthodox stylist for Joe to read and exploit. Cazaghe depends on predictability and would thus get caught early with something unanticipated and untimable due to that unpredictability of Jones's shots and that demon speed. It would happen when Calzaghe is coming in or squaring off or both. I don't care how good his chin appears to be, eating a Jones shot when coming in is going to rattle him to his toenails. Calzaghe would then make a sensible adjustment... the adjustment would be to revert to fundamentals and try to exploit Jones' lack thereof. Jones leaves windows open and Calzaghe would have to find them and catch him with straight, disciplined shots. It wouldn't work for two reasons -Jones won't have much respect for Calzaghe's power and I am not sure that Calzaghe has enough of a swat to force Jones to respect him. Jones would become the stylist, would dictate the tempo, and would likely rattle Calzaghe again because his hand speed cannot be timed and the shots are unpredicatable. Calzaghe would end up fighting like Kessler did and Jones would look like Calzaghe only with more speed and far more power.