David Pinto refers to an e-mail dialogue we have had regarding this year's ballot and first-ballot inductees generally.
His information regarding historical patterns of first-ballot inductees is very enlightening. However, he drops in the following conclusion:

As time goes on, I believe the percentage of first time ballot elections will continue to rise until we have about 90% of players being elected on their first try.

I'm not sure why he believes that, but I don't think it's true. I think that a large part of what makes for first-ballot inductees is the timing of when players retire. Even though the large backlog of deserving candidates has essentially been cleared away, as Pinto notes, there's no reason it can't be replenished to a degree - enough so that 90% just seems far too high.
More specifically, I think that Pinto doesn't account for the historical factor that Bill James alluded to in the 1986 Abstract when he developed his system for predicting HOF induction based on historical patterns, and in his book on the Hall of Fame: voters (especially the Veterans Committee) have historically not adjusted sufficiently for extreme playing conditions. What that means is that as the players who compiled their stats in today's hitter-happy era retire (and assuming that conditions move somewhat closer to a center, which is already happening), many of today's hitters, with their gaudy stats, may eventually gain induction into the Hall as time passes and voters forget the historical context (especially if the Veterans' Committee continues in any substantial form). That forgetting may take time, which may lead to players getting in after a while on the ballot (and it will also take time to sort through the many players likely to retire with vaguely similar and inflated stats).
Later tonight or tomorrow, I hope to post more on this year's candidates for election