No doubt they are amateurs in name only.
Returning to the poll...
I'll rank them...
1) NHL - stick handling, shooting and tape-to-tape passes on a semi-consistent basis with no regard to various checks (poke, stick, or body) is no simple task. Now do it on a sheet of ice with a pair of razor blades strapped to your feet traveling backwards.
2) NFL - Save for kicker, and maybe longsnapper (provided you didn't have to go down and tackle a ball carrier), a layman runs a serious risk of getting murdered. Even if they are hidden at wideout, the O/U for broken fingers would be set at 9.5 and the smart money is on the Over for a 61 mph screen pass. Granted they were not Rec league weekend warriors, per se, but On the other side of the argument are Kurt Warner, who went from the Arena League to Safeway to the NFL to Canton and Bernie Parmalee who had more than just a cup of coffee with the Dolphins.
3) MLB - The hardest thing to do in sports is to hit a round ball with a round bat, squarely. Late inning defense is one of two actions a rec league player could do, (but not particularly well), which leaves pinch runner from third base and only third.
4) NBA - A decent 6'-2" Rec league player may be able to catch and shoot coming off a pick. He could probably successfully inbound a ball more often than not as well.