Looking at the Fangraphs leaderboards over the last couple of months, I have noticed some dramatic drop-offs in production from some hitters from 2010 to 2011.  Since I was curious about it, I decided that I would try to compile a list of the players hitting better or worse than last year.

Here are the parameters:

-The entire Fangraphs leaderboards for 2011. n = 190 players.  I added Panda even though he doesn't qualify for this year.

-2010 players with 400 or more PAs.  I wanted to be able to include some players like Posey.  However, the PAs value is sort of arbitrary.  Though the n = 205 and in my mind it made some sense to have the numbers similar.

-I was going to compare wOBA as that is my favorite metric, but comparing small decimals doesn’t make intuitive sense (to me).  Instead I used wRC+.  This turned out to be a good decision (I think) because the numerical difference between 2011 and 2010 is a percentage difference.  Once caveat that I know of (let me know if you can think of more): while wRC+ is scaled for players during the year, it is not scaled across years.  This means that the value of 100 in 2010 isn’t the same as 100 in 2011.  However, the difference should not be that great, just a few percentage points.

-I eliminated all players with an absolute value less than 25.  This leaves a list of 70 players.  Essentially, this list is comprised of players exceeding their wRC+ from last year by 25% or more or doing worse by 25% or more.

-One thing to remember: this is a list of deltas, so a player like Tulo is still hitting above average, but he just mashed last year and so he has a value of -33.  The same applies in the reverse.

This could obviously be done combining multiple prior years, but I didn’t do that, so do it yourself!

I think the “bad” part of the list is really interesting.  There are some great players down there.

Anyway, here is the list: