Brady Quinn had a nice career at ND and put up some big numbers, but if we are being completely honest about his arm talent, it wasn't what you are describing. While Brady had prototypical size for an NFL QB, he had only average deep ball strength--he had nothing close to Everett Golson's arm, for example--and he wasn't particularly accurate with deep or intermediate throws. Don't forget Brady was throwing to some pretty good WRs and TEs at ND: Jeff Samardzija, Mo Stovall, Rhema McKnight, Anthony Fasano, John Carlson, etc., and they probably covered up some of his accuracy issues. Many thought Brady would be a top 10 NFL draft pick because of his size and the numbers he put up at ND, but in his workouts before the 2007 NFL draft he failed to impress the scouts with his either his arm strength or his accuracy, and that is one of the reasons he dropped down the draft board. Once he got to the NFL, his accuracy problems continued. When you play in the NFL, the QB has to be able to put the ball in tight spots. Brady struggled with that, and that is why he had a fairly lackluster NFL career. I love what Brady Quinn did at ND, but that is an honest assessment of his arm talent.
I haven't watched enough of Tyler Buchner to assess his throwing arm, except to say that he has an unorthodox throwing motion. If he can put the ball where it belongs that won't matter, but I guess we will see if he can. He is pretty clearly an elite running QB, but the jury is out on whether he will be able to rely upon his passing skills to move the team down the field when we need him to.