garf112 wrote:if you aren't playing to win every year, you aren't playing correctly.
Agreed. The worst part of keeper leagues is when people decide to give up two out of three years in order to amass a great team every three years.
But largely, there are so many different flavors of keeper leagues, that its' tough to answer "what they entail"
The three major factors of any keeper league (aside from the categories and number of teams - which is universal) are:
1. The number of keepers allowed
2. How long you can keep players
3. What it costs to keep them.
#s 2 and 3 cause the most variation.
For instance, there is one common keeper set up where you just keep your top "x" players. Say it's 5 keepers. Everyone has 5 keepers and then you draft. In a 12 team league, it pretty much means that the top 60 each year will be kept, with some bias towards players outside the top 60, who are young and have significant upside (e.g. Upton, Gallardo, Bruce, Brett Anderson)
Another common keeper set up is where you again keep "x" players, but this time the cost is based on where you drafted them (or in an auction league - what you paid for them). Clearly Albert Pujols is better than Joey Votto, but in a league where you drafted Votto in the 18th round or paid $4 for him last year, then keeping Votto in the 15th round or for $7 (most keeper leagues inflate the cost of keepers each year) is a much more attractive value than keeping Pujols again for $50. In these leagues, it's more about keeping the most value as opposed to the best players.
But the most frustating thing you'll come against in any keeper league is people giving up this year in order to amass value for next year. Someone who doesn't think they can win the championship will trade away their entire team in May for Colby Rasmus and Matt Weiters, which will basically give another team the championship. There are some ways you affect this (by limiting keepers, limiting trades, making some prospects ineligible to be traded before a certain window, etc.