At-will employment wouldn't make sense in professional sports. Imagine a team that got eliminated in the first round of the playoffs. A player could give two weeks notice and then join a team that was still competing.
Contracts would still exist, as well as a few other rules, but for the most part there wouldn't be things like a salary cap.
European club soccer is much closer to this model and it both creates really strong competition at the top end and a large spread between the top and bottom teams in a league. It is also very difficult to move from the bottom to the top without a huge amount of outside revenue.
Pro sports leagues in North America tend to operate as a monopoly, allowed because they have a union to balance it out. That's why both the NHL and NBA settled their lockouts right before the unions were able able to de-certify (NHL) or file an anti-trust (after decertifying in the NBA) lawsuit.
European club soccer is much closer to this model and it both creates really strong competition at the top end and a large spread between the top and bottom teams in a league. It is also very difficult to move from the bottom to the top without a huge amount of outside revenue.
No, it doesn't. The disparity in athlete talent and revenues between teams which make the Champions League and those which don't is greater than the disparity between say, the NFL and high school football. For the past decade, the winning teams of the Champions League and its feeder legs have all been one of the top 3 highest-spending teams in their respective leagues. There's simply no contest between, say, Manchester United and some random Irish club. In contrast, most of the professional American leagues reduce the talent disparity enough that either team could realistically win a match.
I may not have picked the best wording, but basically I'm agreeing that overall the disparity is very high. The upside is that games like Man City v Man U or Real Madrid v Barcelona end up being very entertaining.
