He proved himself in the Pacquiao fight and Cotto 2. Had Cotto under similar pressure to fight 1, only Cotto came to the dance with a lot more stamina and an infinitely better gameplan.
He proved he was loaded against Cotto in the rematch. Cotto's face didn't look half as damage throughout rounds 7-10 as they did in the first fight. Sure it was Cotto's movement that and stamina that improved but for a reason, Concreto's punches weren't as effective to stop/slow him down as they did in the first fight. If you notice in the first fight, Cotto was fighting similarly till he was pinned on the ropes, that's when he had to absorb loaded punches which quickly broke him down and slowed him. When was the last time Concreto seriously damaged opponents early as he did with Cotto in the first fight?. Against Pacquiao he proved he was beyond loaded as well, the only punch he hurt Pacquiao with was a body shot, that was the highlight of the night for him. Any body shot landed at the right place and at the right time would hurt anyone so it definitely doesn't prove anything. The rest was him getting plowed from one corner to another and sent half blind into retirement.
Any body shot that lands at the right place would hurt, very simple really. Concreto also landed head shots in the fight that did nothing. Pacquiao's power is what forced him to back off and rethink coming forward face first as he usually does.
Ortiz is a head case who would have his moments early. He would then wilt mentally under the pressure.
You answered your own question. Stamina and movement. He got hit a lot less so his face looked a lot less damaged. That's to be expected, no? I'm not saying that he didnt have loaded gloves for fight 1 because i dont know; Im just saying that he proved that he is still a top fighter with or without the bricks, and he would easily defeat Ortiz, and anyone else on that level.
Ortiz has no heart and he would fold down the stretch to Margarito's pressure. He has better boxing skills than Margarito, but not a better chin, heart, endurance, etc... Margarito by late round TKO
Ortiz doesn't have the mental toughness Margarito will pressure him, smirk at all of Ortiz's punches, and smother him into a late TKO