A two player keeper league is the most efficient and effective way to foster year-to-year competition in PSAS both fresh and lively. In a 12 team league, a two player league would keep 24 players out off the draft board. Let's assume a basic scenario. Assume the keeper players were:
12 RB
6 QB
6 WR
If we go strictly by last year's statistics we might expect that there would still be 7 RB with over 900 yards rushing still available at draft time. A similar hypothesis would leave 8 WR with over 1000 yards, and 5 QB with over 3500 yards passing. Additionally, a two player keeper league will significantly alter draft strategy. For example: let us assume that Revenge of the Sith would keep Johnson and McFadden, thus effectively covering them for running backs. With their #1 pick they would still likely be able to take a Matt Ryan at QB or a Calvin Johnson at WR. You can use your imagination to suppose how the draft strategies would be different for squads electing to keep a QB-RB, RB-WR, or QB-WR combination.
Two player keeper gives all the teams an elementary amount of continuity from year to year. It essentially allows everyone to keep the best draft/waiver picks they made last year and learn from all other mistakes or smart picks. You might say that two players is too much, that it will calcify the league, removing the fun of the draft and enshrining a permanent league aristocracy. But, consider that there will be a considerable number of intangibles to contend with in assessing player values year to year, among which we might count injury, strength of schedule, teammate participation, rehabilitation, coaching changes, contract disputes, labor agreements and global climate change. There were three 1000 yard rushers this season who were not starters when the season began. 5 of 2009's top 10 rushers were not in the top 15 in 2010. The point is that a lot more goes into to selecting who you keep and who you don't than you might suspect. There is also of course, the freak factor of the NFL. What if Tebow starts for Denver next year. Will he be kept from Vick's bench, or drafted? In the first round?
It might also be argued that some teams do not actually have two players worthy of keeping. While this seems manifestly impossible, and irrelevant anyway since it's probably their own fault, let us examine the case of Skins All the Way. It is true, that many teams are short on running backs. But the Skins have the option of taking Josh Freeman and Larry Fitzgerald. A top 15 passer and a top 10 receiver. With their #2 pick, they could still probably pick up a Cedric Benson, or a Matt Forte. Sure, it's not ideal. But the theory is that most of the teams who have something to complain about re: weak keeper options, will draft in the top 6 anyway. So, while they won't have their pick of the litter, there's still a lot of room to strategize their way out of a hole with the keeper. If you think about it, the relative weakness of some team's keeper players will actually make the draft more interesting - since, statistically at least, a disproportionate number of top players exist on a few teams. Some of these extras must be cast back to the draft, so if poorer teams can use their keepers to secure their quality role-players, some surprising names may be available come draft time.