Otamendi's biggest problem was diving in unnecessarily - didn't matter whether it was the first or last minute. He no longer does this. That's not down to doping.
Actually, it could be.
Here is how it could be. He was diving in because he was half a step too late, or just didn't have the get up and go to cover the guy like a wet blanket in those situations. Put him on a cycle or two, his physical performance increases by 15% or so, and suddenly, he doesn't feel stretched in those situations. He doesn't feel the need to lunge in.
For anyone who is out of shape, you can test how this works with just a little hard work. If you're in shape, you can test how this works by letting yourself slide.
If you're out of shape, go play a pickup game (whatever sport). Notice how you can't move how you'd like. You find creative ways to cheat on movements. You will foul more when defending. Now, go hit the gym and trainer for 2 months. Be dedicated. No go back and play a pickup game again. You move better. You don't need to cheat on movements you once cheated on. You CAN foul as much, but you don't need to.
That's how a guy who lunges into tackles, can go from diving into tackles he shouldn't have needed to, to stopping all off of PEDs. I'm not saying he is doping. I'm just saying that that is the kind of influence doping can have on ANYONE, in ANY SPORT. The impact of being fitter, faster, stronger goes so far beyond just being fitter, faster and stronger. It can fundamentally change how you play the game, because you're fitter and faster, everything is happening slower for you. You have confidence in your physical abilities, giving you more confidence in your mental game. Your mental game improves because you fatigue less. Your game doesn't drop off, because you fatigue less. You don't start getting sloppy, or cheating proper technique. You can play harder, for longer, at a higher level.