I'd probably go for Joe. But this would be a very fast paced and tactical fight. Both of those guys could move and were skilled as well as being well conditioned. Neither were terribly huge hitters, though sergio could crack from time to time when he had to ( see Paul Williams rematch. ) I think Calzaghe takes it by a decision but it would be a good match.
Martinez is a small middleweight. Joe calzaghe is a sizeable supermiddleweight. Joe would be drained at 163lbs. But anyway joe calzaghe may even stop him, if you are talking prime zaggers who had a decent punch before his hands failed him.
This is a tough one to call because of the weight. First, both fighters fought in lousy eras with thin talent pools. Sergio was a smallish middleweight at best who moved up (from light middle after starting at welter) because he could to find the better fights and face the better comp for better money. Joe was a big super middleweight (by frame/girth) who starved himself to stay at SMW as long as he could to avoid facing any bigger men and better comp up at LHW. Joe and his management generally were content to milk a two-bit belt (in front of a sufficient audience willing to pay to watch the only Welsh big fish in a tiny puddle of water deep in a well) and carefully pick opponents and the timing of the matches to minimize any risk. Sergio is (was) already giving away size in every fight at 160 (middleweight) so 163 does not serve him any better at all. Against the right fighter, it would certainly increase his disadvantages significantly (e.g, Golovkin could scale in at 163 for a catch-weight fight with no difficulty and be stronger for the extra weight). OTOH, Joe would be in incredibly difficult straights just sacrificing those 5 lbs. He was a stick when he fought Reid in early '99 and it would take a young version of Joe to even imagine scaling down to 163 (not the later version in his long career). Joe never had any upper body development as any real muscle would have immediately pushed his thick frame straight out of the 168 weight class. He didnt run those hills because he loved the countryside. At 163 he would be the worst combination of less power with a somewhat minimal size advantage (about 2 or 3 cm in height only) over Martinez. Both fighters actually have the same reach. Martinez as a middleweight fighting at 163 would be an older more schooled fighter or version approaching his mid-30s. Calzaghe as a super middleweight cutting to 168 would have to be a young version because the older one (which was more schooled) could never make 163 safely. Joe would have to be 26 or 27 years of age. But, Sergio is a league or large step better in the guile and slickness category having had far more sparring and work in the US to hone his ability to feint, misdirect, and lead his opponent into shots that are not expected or anticipated. Joe, on the other hand, spent far too much time sparring domestic talent and other weak fare in FWs stable and would be easily feinted out of his shoes when trying to walk down the smaller man and would walk into shots (and the same ones over and over). Getting past the challenge of two leftys meeting up, Sergio has the better technique with a good straight left and a good right hook. Sergio is definitely not going to get out unscathed but as evidenced against the southpaw Williams in two fights his offensive and defensive abilities are better than Calzaghes and it is simply an issue of Joes size and engine that will pose the main difficulties in theory. But, it was clear from watching young Joe against Eubank as well as late in his career against two senior citizens that he had many holes in his game (that were never remedied) as his familiarity with crafty fighters was lacking. With comparable reach Sergio would be beating Joe to the punch as he closed and would find the target with hard shots on many advances. Joe, with his usual size advantage now tempered by having to come in so light as to be almost anemic, would be hard put to implement his time tested fallback strategy of "I'm going to just come forward all night and try to throw more punches than you which worked so well against old men well past their physical prime or domestic level European fare. Joe would be less sturdy at 163 and if he looked skinny against Reid with pin legs and zero upper body muscle development in his arms and shoulders then he would be really something to see five pounds south of 168. The smaller Sergio would surely find him easy to time and land on. Joes resiliency would likely be quite mitigated by the weight loss. This one goes to the cards. Sergio gets a cut eye from a couple of head clashes as Joe pushes forward all night trying to press. Joe comes out with a black eye, bloody nose and split lip from clean punches he walks face first into them regularly. But in the end - Joe edges the fight in a split decision as two British judges (reverse the third non-British judge's 7 -5 card for Martinez) hand him the narrow win in Cardiff. Martinez shakes his head in disgust at losing a fight he believes he won.
Similar styles. I do question whether Calzaghe could get down to 163 lbs. My gut is Calzaghe would win a close decision mainly because he's beaten bigger, stonger guys and would probably have a strength advantage if he wasn't weight drained. I actually don't think Calzaghe would have taken this fight unless it was at 168 lbs.
