I think we should be able to view league leaders for prior years.  This allow you to compare how a player has done against other player and is particularly helpful when evaluating by position.   For example, a .760 OPS might be league average but might be great for SS but below average for 1st base.  All the information for prior years is available already under the player and the team and I would not think it would be difficult to continue to haveit avaialble for each year after the season is over.  It is something that is available for MLB and HBD should also have it.