In sparing Manny has knocked down Shawn Porter who is much larger and they wear large gloves for sparing. I know he can hurt Cotto with the smaller gloves. Cotto is the larger man so I am sure he could hurt Manny to but Manny has been working on angles for his fight with Cotto.
Because nobody knows exactly what takes place behind close doors. It's pure speculation at best, and it's usually used as a mental ploy against the opposing fighter. Even if you were to take the face value of each story, and lets say we did. How many times do you hear a fighter having the best camp and getting a beat down. Furthermore, "supposedly" Floyd was struggling against his sparing partner (Peterson), and Vitali Klitschko as well having a sub-par training camp-well look at the results of there fight, and that's just two examples out of the plethora ones I can mention. One comparable analogy would be The Detroit Lions who were 4-0 last year in the preseason, did that mean ****? No. They went 0-16 during the regular season.
There's a popular quote about this... "Kill yourself in sparring (training) and the fight will be easy..."
its actually "kill yourself in training and the fight will be easy" but you slipped sparring in there so as to legitimize your claim.