How do Different Types of Hitters Age?

It's the baseball offseason, which means that the baseball free agent season is still going on.  Most of the better players have already been signed, but there are still a few players available.  One thing that needs to be considered is how baseball players age.  If you are a general manager signing a 30 year old player to a long term deal, you need to know that your player will not only be good this year, but will also be good in 5+ years.

Most baseball players will peak in their late 20s or early 30s.  They also generally hit free agency for the first time at around age 30*.  If you are going to spend big bucks on a star hitter, you want to make sure they turn out well and you don't regret the deal in two years.  Better yet, you want to be happy with the deal in the last year of the deal.  So how should a general manager play the free agent market?

To figure this out, I took a list of baseball players who played Major League baseball from age 24-40, with up to two or three years where they didn't play (i.e. they could play from age 24-38 and be on the list, or they could play from 24-33, be injured when they are 34 years old, and then play from ages 35-39).  In addition, I tried to make a list of players who finished their career in 1995 through today (and there are a few players on the list who are still playing today).  I also tried to eliminate players who were either caught with steroids or whom it was generally assumed used them.  Barry Bonds, Mark McGwire, Miguel Tejada, Sammy Sosa, Brady Anderson, and Manny Ramirez were taken out right away since their stats may skew the overall stats.  In all, I got a list of 84 players.

First, I separated the players based on their career equivalent runs (a combination of OBP and Slugging Percentage which was explained on a prior post).  I divided the group of 84 players into 4 groups: Group 1 had the 21 players with the highest equivalent run amount, group 2 had the next highest, group 3 had the next highest, and group 4 had the lowest.  Here is a listing of the players in each of the 4 groups:

Group 1: Frank Thomas, Todd Helton, Larry Walker, Jim Thome, Edgar Martinez, Chipper Jones, Mike Piazza, Gary Sheffield, Ken Griffey Jr., Jim Edmonds, Wade Boggs, Bobby Abreu, Fred McGriff, Moises Alou, Ellis Burks, Tony Gwynn, George Brett, Jorge Posada, Rickey Henderson, Jeff Kent, Luis Gonzalez

Group 2: Derek Jeter, Mark Grace, Eric Davis, Andres Galarraga, Paul O'Neill, Eddie Murray, Tim Raines, Matt Stairs, Bobby Bonilla, Paul Molitor, Barry Larkin, Dave Winfield, Harold Baines, Reggie Sanders, Chili Davis, Kirk Gibson, Kenny Lofton, Wally Joyner, Craig Biggio, Raul Ibanez, Dave Magadan

Group 3: Lou Whitaker, Julio Franco, Jeff Conine, Johnny Damon, Tony Phillips, Ivan Rodriguez, Andre Dawson, Brett Butler, Cal Ripken Jr., Brian Jordan, Mike Cameron, Alan Trammell, Todd Zeile, Garret Anderson, Randy Velarde, Steve Finley, Eric Young, Joe Carter, B.J. Surhoff, Gregg Zaun, Lance Parrish

Group 4: Damion Easley, Willie McGee, Devon White, Mark Grudzielanek, Gary Gaetti, Marquis Grissom, Tim Wallach, Mark McLemore, Benito Santiago, Craig Counsell, Sandy Alomar, Omar Vizquel, Shawon Dunston, Ozzie Smith, Otis Nixon, Brad Ausmus, Miguel Cairo, Lenny Harris, Tony Pena, Jose Vizcaino, Henry Blanco

Basically, what I did was found the equivalent runs for each of these players at each age from 24-40.  Then, I found the average Equivalent Runs for each group at each age (for example, At age 24, Group 1 averaged 6.371 Equivalent runs... a team of nine average 24-year old Group 1 players would average about 6.371 runs per game).  Then, I put them onto a line chart and wanted to see which group ages best.  Here's what the graph looks like:

 Basically, from age 24 to age 33, there is a very consistent difference between Group 1 and the rest of the group.  If you are a GM and you want to sign a free agent Group 1-type player, you should expect to pay a lot more and get a lot more (1+ equivalent runs per game... a very significant amount).  A group 4 player will be about 3 equivalent runs worse than a group 1 player from age 24 to age 33.  While group 4 is the least valuable hitting group in this analysis, the players in that group are generally good players (there has to be a reason they stay relevant until their late 30s).  Keeping in mind that even the most mediocre baseball player (cough Cesar Izturis cough) can score about 1.7 equivalent runs over the course of a season, signing one superstar at age 27 or 28 will generally be a better decision than signing two Marquis Grissom types at age 27 or 28.  Signing one Jim Edmonds at age 27 would be better than signing a Sandy Alomar and an Omar Vizquel at age 27.

However, at about age 34 or 35, the top three groups take a step down but group 1 takes the biggest step down.  Players in group 4, however, seem to stay around the same or even get better through age 37.  If you are signing a super star at age 30, you will generally have to sign the player for at least 6 or 7 years.  You may get a great 4-5 years followed by a good, but underwhelming 2-3 years.  However, you will likely get closer to what you pay for from a group 4 type player when signing a long term deal at age 30.  It's funny how 2-3 short years make such a difference; at age 27-28, signing a super star for 7 years is a better idea than signing two average players for 7 years.  But, at age 30-31, signing 2 average players seems like a better idea.

So we got a little bit of an idea about how the overall ability of a hitter should be taken into account when signing a hitter for the long haul.  How about different types of hitters?  Instead of great vs. average in this case, I decided to look at OBP vs. Slugging %.  Basically, I took the OBP portion of the equivalent run statistic and divided it by the equivalent run statistic.  Better OBP players are in group 1 and better slugging players are in group 4.  Here is how the groups shook out:

Group 1: Otis Nixon, Ozzie Smith, Dave Magadan, Mark McLemore, Craig Counsell, Brett Butler, Omar Vizquel, Tony Phillips, Brad Ausmus, Rickey Henderson, Jose Vizcaino, Wade Boggs, Lenny Harris, Eric Young, Tim Raines, Gregg Zaun, Miguel Cairo, Kenny Lofton, Julio Franco, Randy Velarde, Mark Grace

Group 2: Tony Pena, Lou Whitaker, Mark Grudzielanek, Alan Trammel, Derek Jeter, Willie McGee, Tony Gwynn, Craig Biggio, Barry Larkin, Bobby Abreu, Wally Joyner, Paul Molitor, Damion Easley, Todd Zeile, Johnny Damon, B.J. Surhoff, Henry Blanco, Edgar Martinez, Chili Davis, Jorge Posada, Jeff Conine

Group 3: Marquis Grissom, Sandy Alomar, Paul O'Neill, Devon White, Tim Wallach, Harold Baines, Mike Cameron, Luis Gonzalez, Cal Ripken Jr., Kirk Gibson, Bobby Bonilla, Gary Sheffield, Todd Helton, Steve Finley, George Brett, Eddie Murray, Benito Santiago, Chipper Jones, Raul Ibanez, Matt Stairs, Eric Davis

Group 4: Dave Winfield, Frank Thomas, Fred McGriff, Brian Jordan, Ivan Rodriguez, Shawon Dunston, Lance Parrish, Gary Gaetti, Jim Thome, Moises Alou, Jeff Kent, Ellis Burks, Jim Edmonds, Garret Anderson, Reggie Sanders, Larry Walker, Andres Galarraga, Mike Piazza, Ken Griffey Jr., Andre Dawson, Joe Carter

I did the same thing as I did on the chart above and here are the results:

In this case, it appears that slugging percentage players start out as much better run producers than on-base gurus.  At age 27, where Group 4 takes its first peak, the difference is about 1.5 equivalent runs, which is a significant amount.  However, slugging does not age as well and over time.  On the other hand, on-base gurus stay about the same and even get a little better from age 24 all the way to age 37.  As a matter of fact, the on-base gurus bring the difference with group 1 to within about half a run at age 37.  As an FYI, I included age 39 and 40 on this chart, but the sample size diminishes significantly as many players are done after age 38.

One interesting pattern in this chart is that the "middle of the road" type players (groups 2 and 3), remain closer to group 4 than group 1 and actually get better and closer to group 4 over time all the way to age 39.  From age 24 to 33, the difference between the middle groups and group 4 is about 0.5 runs; slightly less than the difference between the middle groups and group 1.  However, by age 37, the difference is significantly less and almost non-existent.  By looking at this, it appears that sluggers start very well, but decline over time.  On-base gurus start below average and get slightly better until their mid-30s, but don't ever come within 0.5 equivalent runs of the sluggers in the group.  The middle groups start right in between sluggers and on-base gurus, but get closer and closer to the slugging group until they are essentially at the same level.

Therefore, I would argue that, in free agency, general managers should want somebody who is good at both getting on base (i.e. taking walks) and slugging (i.e. getting extra base hits and home runs) than someone who is significantly better at one than the other.  If the choice is between on-base gurus and sluggers, getting an on-base guru would likely make more sense since they will likely be cheaper and will decline less than sluggers.  Signing a slugger will very likely result in an overpayment; it's a lot less likely for the hybrid (good OBP and Slug%) players and the on-base gurus.

So here's what I take from this analysis:

• It is better to sign a super star at age 27 than two average players at the same price.
• It is better to sign two average players at age 30 than a super star at the same price.
• "Hybrid" hitters are the best free agent hitters to go after.  These types of hitters generally level out by age 30 but don't get worse until their late 30s and produce very well.  Players like this include Edgar Martinez, Chili Davis, Jorge Posada, Jeff Conine, Marquis Grissom, Sandy Alomar, Paul O'Neill, and Devon White.  Obviously not everybody works out, but there's a better chance with these players.
• If there is a choice between a strict slugger (i.e. Joe Carter) and a strict on-base player (Otis Nixon), go for the on-base player.  While they won't produce as well, they will likely be cheaper and they are more likely to be underpriced since on-base gurus generally level out or even get better until their late 30s.  Sluggers tend to decline starting at about age 32.
• Dave Magadan was underrated.  This is totally off topic, but his career equivalent run amount was 5.395 (a team of 9 Dave Magadans would score, on average, 5.395 runs a game).  A team of 9 Cal Ripkens, on the other hand, would score about 5.128 runs a game.  A bit off topic, but something I noticed from this analysis.

(*For those who don't know, the first six years of a player's Major League career are controlled by the team that drafted them.  The player is paid basically what the team wants to pay them for the first three years and for the next 3 years, the player and the team either sign deals closer to market value or go to arbitration to determine salary.)