Nature of the unknowable

It's been said before, and repeated often enough, that Landon Donovan will not get better unless he goes to Europe.

While I fully believe this could be true - I submit that it is equally possible that this is not, in fact, true.

History, not only of Donovan, but of other players, does not indicate it to be consistently true, either.

Statistically, Donovan is already one of the best U.S. players in history. He has played the majority of his career in Major League Soccer.

One must deduce that he improved during that time.

So the logic is evident that he improved in MLS.

The argument might more correctly be that Donovan would improve MORE in Europe.

This assumes another unknowable - that Donovan would get playing time to help him improve. Case studies of Bobby Convey, DaMarcus Beasley and Clint Dempsey show this is not a given, and that the arrival of a talented young player abroad is not an automatic boost in performance.

Basically, even if such a thing were quantifiable (how would one measure it other than very subjectively?) the evidence that Donovan would, in fact, improve more abroad than he would by remaining in MLS is driven by an artificial construct.

-European soccer (or at least three major leagues there) would improve Donovan's play more than MLS because of the increased level of competition.

There's nothing to support this except for opinion, so it creates a circular argument. Other possibilities exist that are just as, if not even more likely.

- If Landon went to Europe, his play wouldn't rise significantly.

- If Landon went to Europe, his play would decrease slightly.

- If Landon went to Europe, his play would stay at exactly the same level.

- If Landon went to Europe, his play would decrease significantly.

All the possibilities are valid, so it bothers me to see so many discussions based on only the first, as if the others don't exist.

If Europe is so wonderful for developing players, why hasn't a U.S. player in Europe come along better than Donovan?