In doing so, Kelly displayed a tremendous blend of tools and athletic gifts that make clear he's among the very best players at the position in recent history.
Arizona State targeted Kelley with a scholarship early -- October of his sophomore season -- and some prominent schools have subsequently followed suit, notably including Nebraska, Texas A&M and UCLA.
Just how good is Kelley?
We posed as a serious question to a handful of respected onlookers with local knowledge how Kelley compares to former Scottsdale Desert Mountain quarterback Kyle Allen at the same stage.
Allen, of course, went on to become a five-star prospect, ranked No. 1 at the position and No. 7 overall nationally in the 2014 class when he signed with Texas A&M, where he has already become the program's starting quarterback.
Just the very fact the question can be legitimately posed as to whether Kelley is in the same league as Allen is remarkably significant in and of itself.
But get this: several people -- a group that includes coaches and professional evaluators -- actually said they gave a slight edge to Kelley at the same age.
If you rewind to the summer of 2012, when Allen was heading into his junior year, he had about the same number of scholarship offers as Kelley does currently, and though he was considered the top Arizona signal-caller in his class -- as is Kelley in his own class currently -- Allen was not nearly as acclaimed as he'd eventually be.
Allen saw a meteoric rise up rankings of various media outlets after stellar showings at various high profile camps a year later, as a rising senior, in a way few players have in recent years.
It will be extremely difficult for Kelley -- currently unranked but a legitimate candidate to eventually be a Top-100 national recruit -- to have the same explosive assault on the national rankings, but it's not out of the question.
Importantly though, with quarterback rankings at this level proving to be an extremely challenging endeavor, it's a speculative conversation to be sure, especially when discussing prospects who check most, if not all, of the traditional boxes.
To be sure, Kelley, who threw for 3,108 yards and 30 touchdowns as a sophomore, has everything you'd look for in terms of so-called measurables. He's every bit of 6-foot-3 and well constructed physically, has very clean and extremely consistent throwing mechanics, drives the football behind impressive footwork, has plus-velocity and spins the ball extremely well.
Kelley's accuracy, at least in this setting, was excellent, especially given how reliably catchable his ball tends to be. Perhaps most impressive was how well Kelley saw the field, Numerous times he got to his third or fourth read on a given play, often on the backside, and did so within a matter of several seconds. Sure, there's no pass rush, but the tools are clearly there in spades.
This isn't the only setting we've seen Kelley excel at this off-season. He was also terrific in The Opening Los Angeles regional several months ago.
We observed Allen in the same settings, including at ASU's passing league event. If you put 16-year-olds Allen and Kelley side by side in a competition to ascertain who has better accuracy, release quickness, ball velocity, etc., odds are very good there wouldn't be a clear-cut distinguishable winner.
There are of course a lot of things Kelley will have to work on to fine tune and further develop. After all, he's only going into his junior year of high school. He's going to have to develop more finesse on certain throws that require it, for example. But what will ultimately determine how successful Kelley is, just as with Allen, is how well developed his approach to the game is from a mental standpoint, and what his processing power enables on the field in terms of spatial recognition and quick thinking.
For all quarterbacks, football is ultimately a game of chess. It's just that few among them -- a group that includes both Allen and Kelley -- are able to start the game with all the pieces on the board.