Article on player aging curves

[John_Havok]

From Fangraphs, very good read.

 

http://www.fangraphs.com/blogs/hitters-no-longer-peak-only-decline/

 

Since steroid era, players wOBA declining further and starting that decline sooner. Cano contract looking better and better!

[KingKat]

From Fangraphs, very good read.

 

http://www.fangraphs.com/blogs/hitters-no-longer-peak-only-decline/

 

Since steroid era, players wOBA declining further and starting that decline sooner. Cano contract looking better and better!

 

Dude you buried the lead. Players no longer peak, like not at all! On average whatever a player does when he first plays is pretty much what you can expect until he declines. This completely changes how we look at young major leaguers.

[Abomination]

From Fangraphs, very good read.

 

http://www.fangraphs.com/blogs/hitters-no-longer-peak-only-decline/

 

Since steroid era, players wOBA declining further and starting that decline sooner. Cano contract looking better and better!

 

Interesting. I'd love to see one of these studies done with number of games played rather than age though, and see how the curves compare (would give an interesting look at pitcher/hitter adjustments in relation to decline as well)

[NorthOf49]

Very interesting. Too bad we can't expect Mike Trout to get any better

[Captain Adama]

Very interesting. Too bad we can't expect Mike Trout to get any better

 

Blasphemy!

[Frag]

Very interesting article.

[mitchf]

So is this enough data to suggest calling up your specs at 21 years old?

[The Cats Ass]

So is this enough data to suggest calling up your specs at 21 years old?

 

College players straight to the bigs?

[TwistedLogic]

I think there's a few flaws in this study, as people posted on FanGraphs. For one thing, most of the guys you see called up at 21 years old are usually exceptional players, this will skew the numbers for the early years quite a bit.

[NorthOf49]

I think there's a few flaws in this study, as people posted on FanGraphs. For one thing, most of the guys you see called up at 21 years old are usually exceptional players, this will skew the numbers for the early years quite a bit.

Exceptional players don't improve? I'm not sure I see what you mean.

[kcjaysfan]

I'd really like to see error bars on those curves. Without them, they are fairly meaningless.

[The Cats Ass]

Exceptional players don't improve? I'm not sure I see what you mean.

 

They would improve. There's more subpar players in the 25-29 age range then the 20-24 age range. In the 20-24 age range the average- belowaverage players are still in the minors getting seasoning. While the older group is up in the majors filling lesser roles because they have nothing else to work on but still suck.

[TwistedLogic]

Exceptional players don't improve? I'm not sure I see what you mean.

 

I'm saying that the data for younger players will look high because most of the sample for that age group is attributed to high-end prospects that get early promotions (Trout, Harper, Lawrie, etc). It makes hitters as a whole look like the production from age 21 to 25 stays sort of stagnant, when in reality, that isn't exactly true. Most players aren't even good enough to be in the majors at 21. When you group all MLB hitters together, you're getting the great production from guys like Trout and Harper in the 21-23 age group, and then you're getting guys like Arencibia and Thames come in at 24, 25 years old and dragging the average of those numbers down. That doesn't necessarily mean that the Trouts aren't improving with age, it just means that the older they get, the bigger the sample becomes, and the more mediocre talent and journeyman get added into that sample. They should refine their study and compare players that are similar to one-another in terms of when they enter the league and how their wOBA or WAR looks from year to year, as opposed to lumping the entire league into one number.

 

Look at any star player's fangraphs page and you'll see this study debunked several times. If guys come into the league already at their best, and only decline from there on out, why do you see players do things like this so often:

 

http://www.fangraphs.com/statss.aspx?playerid=9847&position=OF

 

2010: 3.5 WAR

2011: 5.4 WAR

2012: 6.8 WAR

2013: 8.2 WAR

 

You're telling me this guy isn't improving and reaching a peak?

 

http://www.fangraphs.com/statss.aspx?playerid=1744&position=1B/3B

 

Stagnating between 5-6 WAR in his earlier seasons, with a few 2.x WAR seasons thrown in. Now he's transcending the 7-WAR plateau and getting near 8 wins.

 

The league as a whole might be more top-heavy now what with all the phenomenal new players coming in at young ages, and the league as a whole might be weaker in the 25+ age range, but that doesn't mean that player's no longer reach a peak before declining. That almost doesn't make sense.

 

You would need data that is far more specific than what these guys have done to determine that.

[Laika]

Hmm. I dunno.

 

If you cut baseball into a bunch of 8 year bins and then make aging curves for all of them, there's probably a chance that a couple of them will look different.

 

So I wouldn't really be inclined to buy the notion that offensive players all of sudden aren't peaking anymore and they're just declining from year 1.

 

Also, if you include defense and playing time, a WAR curve might still have a productive peak.

 

Maybe things like wRC+ and wOBA are appearing to start high and only decline because young players breaking in these days are more likely to be platooned or receive guarded playing time? Maybe young players in general are kept in the minor leagues for longer, so their less productive periods of skill improvement aren't showing up in a big league sample?

 

It's interesting.

[Laika]

I think there's a few flaws in this study, as people posted on FanGraphs. For one thing, most of the guys you see called up at 21 years old are usually exceptional players, this will skew the numbers for the early years quite a bit.

 

I'm not sure that you're really grasping the method used by the author.

 

It's not just wOBA of all 21 year olds compared to wOBA of all 22 year olds, etc. etc.

 

It's the delta between specific player's seasons at certain ages, weighted by plate appearance.

 

So a guy like Stanton, his wOBA actually did improve from age 20 to 21, and then again from 21 to 22, so the data from Stanton individually would influence an improvement curve along that age period on the curve.

[Laika]

The impact of knowledge.

 

From the beginning until 2005, most teams and players in most years didn't really know what made a good hitter. Sure, they thought they knew, but in reality they were more in a fog than they realized. Players were thrown into the big leagues and natural selection took its course. Those that happened to develop the traits of a better hitter at the big league level survived, and the sample in general showed improvement based on natural learning until the late 20's (age).

 

2006 to the present, modern knowledge of developmental factors and hitting skill factors have wiped out this big league natural selection process. Most teams pretty much know what makes a good hitter. Young player development is streamlined and the natural selection process has shifted more to the minor leagues. Players now reach the big leagues as finished products, in general. We don't see nearly as many players throughout their 20's "learning" how to be better hitters. There's nothing for them to figure out on the field. Lots of players still do, of course, but the sample in general shows no improvement from learning.

 

The physical peak of natural athleticism has and always will be something around 20 years old. This should be obvious.

 

Increased knowledge has removed the foggy learning period. Modern baseball now explicitly knows from the get-go what old school baseball used to inexplicitly figure out via a slower, natural process.

 

(this very probably is not true)

[Olerud363]

From Fangraphs, very good read.

 

http://www.fangraphs.com/blogs/hitters-no-longer-peak-only-decline/

 

Since steroid era, players wOBA declining further and starting that decline sooner. Cano contract looking better and better!

 

A lot of my feelings on proposed trades (EE for Price, Bautista for Brown+) are based on assuming these steep declines after 30. That we are returning to an era where after 30 guys go quick.

 

Even younger players look to be declining right away though. I probably am over-estimating the improvement guys like Brown and Beckham have left in them (ie none, other than random variation).

[Dick_Pole]

Did Bud Selig pay for this study? Another impact of eliminating steroids! Seriously it's a flawed study I'm surprised so many people are falling for it. The errors are pretty easy to spot with a lot what Twisted Logic making sense.

[Dick_Pole]

I'm not sure that you're really grasping the method used by the author.

 

It's not just wOBA of all 21 year olds compared to wOBA of all 22 year olds, etc. etc.

 

It's the delta between specific player's seasons at certain ages, weighted by plate appearance.

 

So a guy like Stanton, his wOBA actually did improve from age 20 to 21, and then again from 21 to 22, so the data from Stanton individually would influence an improvement curve along that age period on the curve.

 

But the counter-argument there is that JPA and guys slightly better than him weren't in the league at age 20, 21, 22 to bring the averages of those players down, but he was at age 26, 27 etc.

 

If you want a fair comparison judging guys from age 20 to 30, you need to collect stats only on those players who played in the big leagues for all those years.

[Dick_Pole]

This is something that people really need to use common sense on over believing a study. How many Fred Lynns have there been? Even a guy like Griffey Jr, who was known for fizzling out earlier than expected, had his top WAR seasons at age 26 and 27.

[NorthOf49]

But the counter-argument there is that JPA and guys slightly better than him weren't in the league at age 20, 21, 22 to bring the averages of those players down, but he was at age 26, 27 etc.

 

If you want a fair comparison judging guys from age 20 to 30, you need to collect stats only on those players who played in the big leagues for all those years.

It doesn't matter how good/bad the players in each category are. This study looked at the change in the players' performance by year. Why would players who have been in the Majors for four years by age 26 improve/worsen more than players who have been in the Majors for only two years by 26?

 

With that said, I am skeptical of the significance of this data.

[Abomination]

It doesn't matter how good/bad the players in each category are. This study looked at the change in the players' performance by year. Why would players who have been in the Majors for four years by age 26 improve/worsen more than players who have been in the Majors for only two years by 26?

 

With that said, I am skeptical of the significance of this data.

 

You could argue that it takes the league a certain amount of time to determine a player's strengths and weaknesses, and exploit them. The player then in turn also needs to adjust. After a time, you should reach a relative steady state representing the player's true level (probably overlapping with skill erosion). I would suspect that a lot of the early decline is due to this, with later decline due more to aging. This is why I would like to see a similar study relating to service time rather than age, and see if it produces the same approximate results.

 

I don't know if I'm right or not, just thinking out loud.

[Dick_Pole]

It doesn't matter how good/bad the players in each category are. This study looked at the change in the players' performance by year. Why would players who have been in the Majors for four years by age 26 improve/worsen more than players who have been in the Majors for only two years by 26?

 

With that said, I am skeptical of the significance of this data.

 

Well for one, the players who were in the league starting at age 25 through 26 supposedly improved enough from ages 23 through 24 to get the call to the majors right? But that data is locked in minor league stats and not counted in the study.

 

I suppose that's weakness of the study. It lists one of the reasons why this may occur is that teams keep players in the minors until they are full refined players. They may be ready physically but not mentally, thus are spending their time in AAA at age 23, improving there.

 

This study may or may not be appropriate for measuring someone's physical abilities only, but it takes more than that to be a fully refined MLB player.

[Nox]

If you want a fair comparison judging guys from age 20 to 30, you need to collect stats only on those players who played in the big leagues for all those years.

 

The concern you have is understandable but your proposed method amplifies survivor bias even further (already a problem with the delta method). It also would reduce your sample significantly.

[Nox]

This is something that people really need to use common sense on over believing a study. How many Fred Lynns have there been? Even a guy like Griffey Jr, who was known for fizzling out earlier than expected, had his top WAR seasons at age 26 and 27.

 

We need to be careful with what our intuitions truly tell us though. Before work on aging curves were done, most assumed a players peak was from Age 28-32. That's almost certainly false.