for me... I watch them play. I watch how they interact with their team mates...then I watch interviews when they are available. I look for similarities in other QB's I have seen play over the past 40 years.... then, sadly enough, I correlate all the information I have gathered...and I go with my gut. Some guys have all the stats and measurables and I still dont like them.... Jared Goff for example...even though it appears I was wrong about him...I wasnt wrong about Carson Wentz...way back when... I was pimping Cam Newton on this board 8 months before the draft. Sometimes you just get a hunch about a guy... I really liked Desuan Watson but was concerned his pass velocity would lead to lots of picks in the NFL....remains to be seen. in regards to trading up. It's simple. NFL Quarterback is the single most important position in team sports. At any given time there are less than 30 guys who can play that position effectively.There are also less than 10 who can play that position...uh,...in a transcendent manner... if you see an opportunity to get a guy who can do "A" and you believe he can do "B"...then you do what you have to do to go get him. It's a gamble. Most GM's who make that gamble fail.... but if your a fast ball hitter and Randy Johnson is sending you a smoker right down the pipe you gotta swing...missing does not mean you dont swing again... the fact that he has struck out the past 10 batters does not mean you dont swing... because its a fast ball,...and thats what you hit.