Hmm, interesting observation. Maybe they injected him in different parts of the hand and it started bleeding into the wraps?
Mayweather is a right handed fighter and is far more likely to be hitting a bag harder with his right hand. The best punch he throws with his left is not a power shot.
That wouldn't matter. If the dye came from those gloves it would've bled on both gloves. There was nothing on the other wraps.
If Floyd bled from the training, Garcia would have attended to that ASAP, not by just looking at Floyd. Glove-dye
The marks are in 3 separate sections. Over the middle, and last two knuckles. The fact that there is space between each secion of red indicates that it was caused by the knuckles beneath pressing against something that was red. If he was bleeding beneath his wraps, the blood would spread, be soaked up by the gauze and it would show inbetween the knuckles aswell, it would not be segmented. You can also see a vaguely pink substance on his left shoulder, which again, would indicate die, if he was sparring it would also indicate he has been shoulder-rolling, and the gloves have caught him on his shoulder, and some dye has rubbed off, which would make sense. It's not blood.