Prove to who? You? Me? Sorry, but you and I do not determine who starts and who doesnt. Sage has had several years worth of chances to prove himself worthy of moving up on the depth chart to the people that DO make those decisions. Even if you take into account that while with the Phins he could never start because of the Wanny/Fiedler relationship, he should have at least moved into the #2 spot. 4 years of showing his abilities in minicamps and training camps and he is still 3rd string. AJ isnt a whole lot better....he had to leave the Eagles to be promoted off of 3rd string...but when given the chance in mini/training camps with the Dolphins, he apparently showed enough to be placed ahead of Sage.
Draft position for these guys at this point is entirely meaningless. They are going into their 5th year in the NFL, so it doesnt matter in the least that one guy was picked 1 round ahead of the other. The only thing draft position tells you about a player picked over 4 years ago is how smart/dumb the GM that selected him was.
As to your comment : "So what you are saying that AJ is better than Sage, and everyone knows it, its obvious, but for some reason Sage was drafted ahead of AJ?".....Weaker talent is picked over better talent all the time. Its hard to judge a young players potential coming out of college, but usually a year in the NFL will sort things out. The thing is, after the draft is over you have to throw out all the hype and hoopla about a player and start judging him on what he is able to do in your practices. If he can play...great. If he cant, then he's a benchwarmer. It doesnt matter in the least where he was drafted.