Obviously, one of the difficulties in stating who the best pure athlete is without having criteria. To me the pure athlete is the combination of speed, strength, explosiveness, leaping ability, hand-eye coordination and body control. Not having measures for all that are considered--and even if we did some of the traits are very difficult to measure. But here is my case for each...

Danny Ainge

His exploits as a high schooler are legendary and have not been duplicated (first team all-american in football, basketball and baseball). In college he won the John R Wooden award for the nation's best college player. He played three seasons for the Blue Jays while still in college, but decided to dedicate himself to basketball, where he earned two championship rings and helped three teams make it to the NBA finals. He has a strong case as being the only athlete on the list to play two major sports professionally. And who knows what he could have done in football had he not given that up.

 Taysom Hill

What Taysom Hill is doing in the NFL right now is unprecedented. Granted a lot of the credit goes to Sean Peyton for being open and creative in using Hill's talents.  He's gone from a special teams novelty to playing a critical role in the Saints offense.  His ability to run, pass, block and catch make him a match up nightmare.  He has 4.4 speed and no, Tebow could not do what he is doing right now.  His case can be summed up by saying that due to his athletesism he is doing something that has never been done before in NFL history.

Steve Young

He has had the most professional success of any BYU athelete.  At the apex of his career, it is harder to find a more dominat quarterback (earning 2 MVP awards, and Super Bowl MVP) and only misses lists of the all-time greatest because others have more longevity.  What makes Young unique as quarterback was his high acumen as both a passer and runner.  Defenders dreaded playing him because of his ability to make them look silly.  He is likely the best dual threat QB of all-time, definitely a unique athlete.

Luke Staley

Perhaps the best athlete on the football team is the running back.  Good RBs require speed, quickness, explosiveness, balance and stength.  Luke is the only RB in BYU history to receive the award for best RB in the country.  Luke will always be the great 'what might have been' because injuries derailed a promising career.  Known for his huge calves, Luke is an explosive athlete if there ever was one.

Ziggy Ansah

In a few years, Ziggy Ansah went from not knowing how to put on pads, to a number 5 pick in the NFL draft - the highest ever pick for BYU athelete since Steve Young.  We saw his progression from a wedge buster on kick-offs (never will the mental image of that large man trucking down the field on kick-off coverage leave my mind) to the most dominant DL to ever play at BYU by the end of his senior season.  At the NFL combine he posted ridiculous numbers for a man his size that had NFL scouts drooling.  Injuries have marred a promising NFL career, but someone so agile and fast at his size has never been seen at BYU.

Ossie Attonetti

Because he played volleyball he flies a little under (or over?) the radar, but if explosiveness is the primary criteria, and the vertical is the best way to measure explosiveness, then Ossie deserves the award as the best pure athelete.  Ossie led BYU to its first National Championship and seemed to defy gravity doing so.  In addition, to his jumping ability the hand-eye coordination, quick reaction that volleyball require make Ossie a great candidate for best pure athlete.

Frankie Fredericks

All the athletes above achieved their exploits competeing against atheletes from North America, but Frankie Fredericks exploits were achieved at a global level.  In 1992 and 1996 olympics he won two silver medals each time in the 100m and 200m.  Though his athletic accomplishments were limited to just one measure (speed) of athletic prowess, no one else on the least can claim the level of success he achieved in his sport.  He is considered in the top 12 fastest men of all time.

Everything considered I would order them this way:
1) Frankie Fredericks

2) Taysom Hill

3) Danny Ainge

4) Steve Young

5) Ziggy Ansah

6) Ossie Attonetti