Ideally, you want a CF with lightning jump AND sprinter speed. But, "what if", 2/3 (3/4? - 9/10?) of the speedsters being shoved into CF because of speed really don't have any feel for the ball off the bat?
Is that feasible, bro'?
Couldn't Denard Span, or Jacoby Ellsbury, or any starting ML center fielder, go to the U of Washington and teach the college outfielders how to play baseball?
Do they let guys start in CF in the NL East ... who have not yet been trained how to play?
Was Andruw REALLY done as a star CF at age 24? Because that's the year his triples and SB attempts plunged. Perhaps.
Ya, and if you have very many of these guys whose UZR drops off like that, it's a powerful argument that "JUMP" is much less important than footspeed... if anything, JUMP should get better as the years go by, and the CF gets a better and better feel for pitch trajectories and batter startups...
SSI would predict that UZR age-arcs would reflect speed about 80%, 90%, and JUMPs about 10%, 20%...