You wish that Marquez beat him cleanly? That was as clean a shot as you can get, and he did it twice in this fight. So you're saying without a doubt that Marquez was juicing? What about all those times Pacquiao refused to get tested before possibly facing Mayweather? I believe Freddie Roach tried to hint at Marquez possibly being on the juice on 24/7, but he back pedaled on that comment. I'll have to go back and rewatch it to confirm.
Just because he's this old, doesn't mean Marquez can't improve. Just take a look at Sergio Martinez, almost just as old, at 37 years old, he's at his prime. Not just that, but Martinez started fighting at a much older age than most boxers. Martinez is currently the #3 pound-for-pound fighter in the world, The Ring and WBC Middleweight Champion.