First Pitch - August 29, 2007 - Improving/Declining Hitter Performance

Improving/Declining Hitter Performance

Good morning everybody.  As the season drags on for those of us out of the money, today we will try to determine any hitters that have seen their performances improve this year versus their 3-year averages.  Knowing that regression to the mean is always possible, it will be important for us to examine the players on a case-by-case basis to determine where there is a fluke and where there is some real skills growth, but this should provide us a rough idea of some key players that are either better or worse than their recent past performances.

In order to qualify, a player needed at least 300 AB this season, and an average of 150 or more over the last three years.  Data is through games of August 27^th.  In the data below, DIFF represents the percentage difference between the players current OPS and their 3-year average OPS. 

The first grouping of players are those whose performance (as measured by OPS) has improved by 10% or more this season versus their 3-year average.  While 10% may not sound like a lot, when you look at the OPS values it can be.  For instance, while we can say that Brad Hawpe improved his performance this year by 12%, it doesn't sound like much.  But when you realize that means he increased his OPS by almost a hundred points it sounds a lot better.

Magglio Ordonez has clearly been the most improved player this year, by almost any measure.  Other notables who have improved are: Prince Fielder, Curtis Granderson, Alex Rios, Hanley Ramirez, Chase Utley, Alex Rodriguez, Eric Byrnes.  These are all players that have not only improved this year, but you can also be relatively confident that this is part of a growth curve and not a fluke season.

The second grouping of players are those whose performance (as measured by OPS) has declined by 10% or more this season versus their 3-year average.  Again...while 10% may not sound like a lot, when you look at the OPS values it really can be.  For instance, while we can say that Todd Helton's performance declined this year by 11%, it doesn't sound like much.  But when you realize that means he lost more than a hundred points off his OPS it sounds a lot worse.

Wow.  Now I know what happened to my roto team this year.  Of my original 14-player offensive lineup, 6 of those players are on this list.  This means that almost half of my hitters had disappointing seasons when compared to their recent past performances.  I wish that made me feel better, but it doesn't.  Leading the way here is Travis Hafner, who could be the biggest disappointment of the fantasy baseball season (he's at least in the discussion).  Other notables who have had very off years include: Jason Bay, Andruw Jones, Manny Ramirez, Lance Berkman, Vernon Wells, Todd Helton, and Bobby Abreu.