Sorry for the long post......
I remember before Oscar vs Pac. Nobody gave Pac a dog's chance because they were all focused on the star who was Oscar, really forgetting that styles and abilities win fights not names. Don't just look at Pac and what he can do against other fighters with other styles.
Clottey is not Cotto, Diaz, de la Hoya, Hatton. Clottey is a bigger, better and defensive version of Marquez. He can throw multiple varied combinations, has a sharp right hand, can counter very effectively, is very accurate with his punches and has under rated hand speed. He is a technician, a thinking fighter. Better combination puncher than Marquez? He can throw a triple,quadruple left hook to the body and head, double,triple left or right uppercut followed by hooks, 6 punch left-right hook combination. He's done this against all his opponents. Remember combinations not flurries. He can throw basically any punch in the book: hook, uppercut, straight, jab correctly and fast. He does all this without leaving his defense open. People talk about his activity level but he throws an average of 55 punches around with an accuracy level between 32-50%. The time his activity level drops off really is when his opponents start backpedalling heavily or when he's hurt his hands(even Mayweather was out thrown and outlanded with injury to his shoulder). He never slacks off when his opponents is engaging. Infact he'd thrown 28 punches in less than 1:30 of the 9th round of his fight with Judah.
Clottey is not the most exciting(high activity, extremely offensive) fighter but he's a damn efficient fighter. He doesn't waste his energy in either attack or defense. He thinks about what he's doing and doesn't use just athleticism or natural ability. He uses technique and adapts to fighters as well.
People also forget that Clottey outlanded Cotto in almost every round(including the 1st). People forget he was dominating Cotto from round 7-10. Only a desperate\frustrated fighter will resort to dirty tricks. Watch the fight without the commentary and watch who is landing what carefully. Cotto landed very few punches of significance the entire fight, despite all that he was throwing, whiles eating a steady diet of hard punches. Clottey did all this whiles slipping all over the canvas because of the new painted adverts. He better buy better shoes this time otherwise he'll be KTFO
Pac's going to be in battle against a highly skilled technician and if he doesn't realise that and relies only on his exceptional physical gifts of speed and power(hand and foot) he's going to lose big. You might discount him but Judah is pretty fast and powerful. He got severely beaten up by Clottey, infact Clottey beat Judah up more than even Cotto, so much he preferred to quit than continue to fight.
Pac is going to have to be tactical(and maybe boring), disciplined and perfect to win this fight. He has to stop thinking this is an easier fight because Clottey is not as fast as Mayweather or doesn't move as much. He has to stop thinking only his offense is enough to win the fight. His offense is not the main thing in this fight because he won't land much cleanly. Volume, power, speed are not going to crack Clottey's defense, Margarito threw more than 1600 punches and didn't get through to hurt Clottey, Judah with all his speed didn't get through and Cotto with all his power didn't get through. He has to concentrate more on not getting hit rather than hitting in this fight.
Cotto caused much more damage to Pac than he did to Cotto. Let me illustrate this and Clottey's offense\defense:
After Pac-Cotto: Cotto had swollen eyes, swollen lip, bleeding mouth and nose and Pac had a busted ear drum, swollen eyes, cut swollen lips.
That should tell you about the defense of Pac.
After Cotto-Clottey: Cotto had a swollen eyes, swollen lip, bleeding mouth and nose. Clottey was unmarked.
After Clottey-Corrales(RIP): Corrales had a broken jaw, swollen, almost shut eyes, cut on both his eyes, bleeding nose and mouth. Clottey was unmarked.
After Clottey-Judah: Judah had swollen eyes, cut on his eye(from a punch), bleeding nose and mouth. Clottey was unmarked.
After Margarito-Clottey: Margarito had swollen eyes, swollen head, busted ear drum, swollen lips and had to be in the hospital for 10 hours (can't psot urls now but google 'margarito, hospiatl,clottey'). Clottey was unmarked.
If Pac is not disciplined this will turn out like Shane Mosley-Winky Wright. Shane had extreme hand speed, foot speed, power in both hands, aggressiveness, stamina and mental will. Winky had his tight peek-a-boo guard(like Clottey), a nice stiff jab and size\reach advantage. What happened? Shane was convincingly beaten not once but twice.
More on defense of Clottey, Pac.
1. Pac has been seriously rocked multiple times in many fights and as recently as Marquez II, Clottey's never been seriously rocked
2. Pac's been in trouble in more than 1 fight, Clottey's never been in trouble in any fight
3. Pac's been cut in more than one fight and as recently as Marquez II, Clottey's never been cut in any fight
4. Pac's been outlanded in more than one fight (excluding his losses), Clottey's been outlanded only once (against Margarito, who threw more than 1600 punches when Clottey had injured hands and he still didn't land any significant punch that troubled Clottey)
Slipping, moving is not the only defense available, it's good if you have the reflexes, athleticism and extreme stamina for 12 rounds but it uses a lot of energy and can be time\figured out. Clottey can box on his toes very effectively if he needs to(round 9 or 10 against Margarito) but prefers the high guard defense because it more effective for him. Clottey's defense is in front of you and you know it yet you can't get through or around it. It uses little energy and it's effective to both the body and head.
Clottey's defense, whiles different in technique is as effective as Mayweather's, very few punches land cleanly through his defense. Also, he's in position to counter or launch his offense effectively from it immediately your attack is over because he is really close to you whiles you are punching.
Pac\Mayweather fans will be well advised to really study Clottey (watch his fights, at least full fights against Cotto, Judah, Coralles, Margarito, Baldomir) before making their pronouncement or they'll be shocked at how bad Clottey makes Pac look. Pac may annihilate Clottey as they are saying, but that's a very small possibility. It's a slim as Clottey KOing Pac in 3 rounds(Clottey is an accumulation fighter not KO artist).
This is a tough fight that Pac will probably win but it'll take a lot out of him. He may even have to rely on favourable judges (like in Marquez I & II) to win.