03 February 2014

The Impact of Age on Prospect Success Rates

In previous posts, I’ve written about Baseball America’s success rates predicting which prospects will succeed in the majors. In this post, I want to write about their success rates when taking age into account from 1990-2006. 

In order to determine how successful Baseball America has been at predicting success of prospects based on age, I downloaded all the data for all rookies who had a season of at least 100 PAs or 25 innings in the majors and split them into groups based on whether they were a ranked Baseball America Top Hundred prospect, whether they were a position or pitching player and based on their age when they first entered the majors. The age groupings are 20-22, 23, 24 and 25+. There were very few players that made it to the majors before 20 and all of them were ranked so I didn’t include them in this analysis.

As in previous posts, a successful prospect is one that is worth at least 1.5 WAR per year for his first six years.  If a player doesn’t have at least 100 PAs or 25 innings in the majors his first year than that year is omitted from the calculations (but is still considered the year he enters the majors). If a player doesn’t have at least 100 PAs or 25 innings in either of his first two years than both of those years are omitted from the calculations. His third year is included regardless of whether he has at least 100 PAs or 25 innings.

The first prospects I looked at were position prospects ranked by Baseball America. The following table shows their success rates.

Age  Group Year Group Success    Percent Number of Successful Prospects
20-22 1990-1993 42.59% 23
20-22 1994-1997 48.89% 22
20-22 1998-2002 31.03% 18
20-22 2003-2006 56.52% 26
23 1990-1993 39.39% 13
23 1994-1997 33.33% 5
23 1998-2002 44.44% 12
23 2003-2006 33.33% 9
24 1990-1993 43.75% 7
24 1994-1997 7.69% 1
24 1998-2002 20.69% 6
24 2003-2006 38.46% 5
25+ 1990-1993 16.67% 1
25+ 1994-1997 18.18% 2
25+ 1998-2002 40.00% 4
25+ 2003-2006 11.11%

The majority of successful offensive rookies ranked by Baseball America are between ages 20-22 when they first play in the majors and have the best success rates. Offensive prospects that don’t make it to the majors until they are 23 or 24 still have high success rates. Offensive players ranked by Baseball America that do not make it to the majors by 24 have lower success rates. 

The following table looks at unranked offensive prospects and their success rates:

Age Group Year Group Success Rate      Number of Successful Prospects
20-22 1990-1993 3.70% 1
20-22 1994-1997 13.04% 3
20-22 1998-2002 17.86% 5
20-22 2003-2006 19.35% 6
23 1990-1993 13.16% 5
23 1994-1997 5.56% 2
23 1998-2002 7.14% 3
23 2003-2006 11.11% 3
24 1990-1993 6.67% 4
24 1994-1997 13.33% 6
24 1998-2002 12.24% 6
24 2003-2006 15.56% 7
25+ 1990-1993 4.72% 6
25+ 1994-1997 3.95% 3
25+ 1998-2002 6.90% 8
25+ 2003-2006 6.25% 6


The number of successful prospects remains similar by age but the chance of an unranked prospect succeeding decreases as he becomes older. It is far less likely that an unranked offensive prospect will succeed than a ranked one. Unranked prospects that make it to the majors by 22 have a surprisingly high chance at being successful.

The following tables show the number of successful hitting prospects by rankings.

Age Year 1-10 11-20 21-30 31-50 51-100 Not Ranked
20-22 1990-1993 9 7 1 2 4 1
20-22 1994-1997 6 6 3 4 3 3
20-22 1998-2002 7 2 1 6 2 5
20-22 2003-2006 6 7 3 5 5 6
23 1990-1993 2 2 1 6 2 5
23 1994-1997 1 2 0 0 2 2
23 1998-2002 1 3 1 4 3 3
23 2003-2006 3 0 1 2 3 3
24 1990-1993 2 0 1 2 2 4
24 1994-1997 0 0 0 0 1 6
24 1998-2002 0 0 0 1 5 6
24 2003-2006 0 0 1 0 4 7
25+ 1990-1993 0 0 0 0 1 6
25+ 1994-1997 0 0 0 0 2 3
25+ 1998-2002 1 0 1 1 1 8
25+ 2003-2006 1 0 0 0 0 6  


Age Group Year Group Not Top Hundred Top Hundred Success Rate
20-22 1990-1993 1 23 95.83%
20-22 1994-1997 3 22 88.00%
20-22 1998-2002 5 18 78.26%
20-22 2003-2006 6 26 81.25%
23 1990-1993 5 13 72.22%
23 1994-1997 2 5 71.43%
23 1998-2002 3 12 80.00%
23 2003-2006 3 9 75.00%
24 1990-1993 4 7 63.64%
24 1994-1997 6 1 14.29%
24 1998-2002 6 6 50.00%
24 2003-2006 7 5 41.67%
25+ 1990-1993 6 1 14.29%
25+ 1994-1997 3 2 40.00%
25+ 1998-2002 8 4 33.33%
25+ 2003-2006 6 1 14.29%


It appears that Baseball America was better at identifying top talent aged 20-22 from 1990-1997 than it was in 1998-2006 but still ranked 80% of successful position rookies in that age group. While Baseball America accurately identified a large percentage of top offensive talent that entered the majors from ages 20-23, they were less able to identify top offensive talent that first entered the majors at 24 or older.  Many of the successful ranked rookies who entered the majors for the first time at 24 were ranked from 51-100. 

Another point worth covering is whether these trends remain true for both prospects that went to the majors after high school and those that went to the majors after attending college. This data can be found in a database created by Sean Lehman for all players that make it to the majors. Players that went to either a Junior College or Community College were excluded from this analysis because there were very few of them and the drafting rules for players at either of these are different than those drafted out of high school or a four year college.

This table shows the success rates of ranked offensive prospects based on whether they went to college.

Age Group College Success Rate Number Successful
20-22 No 40.24% 68
20-22 Yes 59.26% 16
23 No 28.57% 16
23 Yes 47.50% 19
24 No 9.09% 2
24 Yes 37.78% 17
25+ No 15.00% 3
25+ Yes 31.25% 5

The majority of successful ranked prospects are those that go to high school and make it to the majors before they are 23 years old. Nearly all high school ranked offensive prospects that succeed make it to the majors before they are 24 years old. Younger high school ranked offensive prospects have a better chance of success than older high school ranked offensive prospects. 

While fewer college prospects between ages 20-22 make it to the majors than high school prospects aged 20-22 those who do have higher success rates than the high school prospects. Like high school prospects, younger college offensive prospects have better success rates than older college offensive prospects.  Unlike high school prospects, ranked college position prospects have good chances of succeeding no matter when they reach the majors.

This table shows the success rates of unranked offensive prospects based on whether they went to college or not.

Age Group College Success Rate Number Successful
20-22 No 13.48% 12
20-22 Yes 21.43% 3
23 No 5.68% 5
23 Yes 13.95% 6
24 No 9.89% 9
24 Yes 13.48% 12
25+ No 4.67% 7
25+ Yes 6.87% 16


Unranked college prospects are more likely to be successful than unranked high school prospects. The earlier that both high school and college unranked prospects make it to the majors, the higher the chances that they will be successful.

Unranked high school offensive prospects are very unlikely to be successful if they don’t make it to the majors when they are 22 or younger. Unranked college prospects are most likely to be successful if they can make it to the majors when they are 22 or younger. Many successful college prospects were successful despite not reaching the majors until they were 24.

The above shows the success rate of offensive prospects based on age. Now, we can do the same analysis for pitching prospects. Here is the success rates for ranked pitching prospects:

Age Group Year Group Success Percent  Successful Prospects
20-22 1990-1993 20.00% 7
20-22 1994-1997 21.43% 9
20-22 1998-2002 44.26% 27
20-22 2003-2006 38.30% 18
23 1990-1993 28.57% 6
23 1994-1997 27.78% 5
23 1998-2002 34.62% 9
23 2003-2006 20.00% 4
24 1990-1993 16.67% 1
24 1994-1997 25.00% 2
24 1998-2002 10.00% 1
24 2003-2006 9.09% 1
25+ 1990-1993 25.00% 2
25+ 1994-1997 6.67% 1
25+ 1998-2002 25.00% 2
25+ 2003-2006 22.22% 2

From 1998-2006 most successful ranked pitching prospects made it to the majors by 22. The ones who did so had a good shot at being successful. Very few ranked pitching prospects succeeded if they didn’t make it to the majors by the time they were 23. While it looks like pitching prospects older than 25 succeeded at high rates, it is important to realize that those numbers are inflated by “prospects” that go straight to the majors such as Jose Contreras and Rolando Arrojo as well as low sample size. 

The next table shows the success rates of unranked pitching prospects:

Age Group Year Group Success Rate Successful Prospects
20-22 1990-1993 22.50% 9
20-22 1994-1997 13.79% 4
20-22 1998-2002 6.00% 3
20-22 2003-2006 2.08% 1
23 1990-1993 2.63% 1
23 1994-1997 7.32% 3
23 1998-2002 11.11% 6
23 2003-2006 5.17% 3
24 1990-1993 10.17% 6
24 1994-1997 10.20% 5
24 1998-2002 5.00% 4
24 2003-2006 6.38% 3
25+ 1990-1993 2.13% 3
25+ 1994-1997 1.65% 2
25+ 1998-2002 3.55% 5
25+ 2003-2006 2.46% 3

From 1998-2006, Baseball America did a very good job identifying the top pitching prospects between ages 20-22. As a result, the vast majority of unranked pitching prospects failed regardless of age.  If this trend continues than very few unranked pitching prospects will be successful.

The following tables show the number of successful pitching prospects by their Baseball America rank or lack thereof.

Age Group Year Group 1-10 11-20 21-30 31-50 51-100 Not
20-22 1990-1993 3 2 1 0 1 9
20-22 1994-1997 1 2 2 2 2 4
20-22 1998-2002 7 4 2 4 10 3
20-22 2003-2006 5 3 4 3 3 1
23 1990-1993 0 0 2 1 3 1
23 1994-1997 1 1 0 2 1 3
23 1998-2002 1 1 1 2 4 6
23 2003-2006 0 1 1 1 1 3
24 1990-1993 0 0 0 0 1 6
24 1994-1997 0 1 0 0 1 5
24 1998-2002 1 0 0 0 0 4
24 2003-2006 0 0 0 1 0 3
25+ 1990-1993 0 0 0 1 1 3
25+ 1994-1997 0 0 0 0 1 2
25+ 1998-2002 0 0 0 2 0 5
25+ 2003-2006 1 1 0 0 1 2

This table compares the number of successful top hundred prospects to non top hundred prospects.
Age Group Year Group Not Top Hundred Top Hundred Success Rate
20-22 1990-1993 9 7 43.75%
20-22 1994-1997 4 9 69.23%
20-22 1998-2002 3 27 90.00%
20-22 2003-2006 1 18 94.74%
23 1990-1993 1 6 85.71%
23 1994-1997 3 5 62.50%
23 1998-2002 6 9 60.00%
23 2003-2006 3 4 57.14%
24 1990-1993 6 1 14.29%
24 1994-1997 5 2 28.57%
24 1998-2002 4 1 20.00%
24 2003-2006 3 1 25.00%
25+ 1990-1993 3 2 40.00%
25+ 1994-1997 2 1 33.33%
25+ 1998-2002 5 2 28.57%
25+ 2003-2006 3 2 40.00%

Baseball America is really successful at projecting top talent from 20-22.  Baseball America has historically had very little success projecting talent that's 24 or older.

We saw earlier that from 1998-2006 that unranked pitching prospects have rarely been successful. The following table can show us whether these trends remain true for prospects that went to the majors after high school and those that went to the majors after college. 

Age Group College Success Rate Total Successful
20-22 No 0.00% 0
20-22 Yes 5.26% 1
23 No 8.70% 6
23 Yes 8.10% 3
24 No 3.22% 2
24 Yes 7.40% 4
25+ No 3.54% 4
25+ Yes 3.01% 4

Very few unranked pitching prospects were successful from 1998-2006 regardless of whether they went to college or high school. There are roughly three successful unranked pitching prospects per year from 1998-2006. This table describing the performance of ranked pitching prospects based on whether they went to high school or college from 1998-2006 is more interesting.


Age Group Year Group College Success Rate Total Success
20-22 1998-2002 No 44.23% 23
20-22 2003-2006 No 42.42% 14
20-22 1998-2002 Yes 50.00% 4
20-22 2003-2006 Yes 30.00% 3
23 1998-2002 No 31.58% 6
23 2003-2006 No 14.29% 1
23 1998-2002 Yes 40.00% 2
23 2003-2006 Yes 27.27% 3
24 1998-2002 No 16.67% 1
24 2003-2006 No 0.00% 0
24 1998-2002 Yes 0.00% 0
24 2003-2006 Yes 20.00% 1
25+ 1998-2002 No 28.57% 2
25+ 2003-2006 No 33.33% 1
25+ 1998-2002 Yes 0.00% 0
25+ 2003-2006 Yes 16.67% 1

A plurality of successful pitchers go to high school and make it to the majors by 22. However, college pitchers that make it to the majors by 22 have similar success rates. Also college pitchers that reach the majors by 23 are more likely to be successful than high school pitchers that reach the majors by 23. Very few ranked pitchers older than 24 are successful.

To sum up, offensive prospects that went to college had a higher success rate than offensive prospects that went to high school regardless of whether they were ranked. However, the majority of successful offensive rookies did not go to college. The majority of successful pitching prospects also did not go to college and success rates for high school and college rookies were similar.

Baseball America was able to determine the best talent that reaches the majors before 23 with the exception of pitching prospects from 1990-1997. It successfully ranked 80% of successful offensive talent and 90% of successful pitching talent that made it to the majors before 23. Baseball America was much less successful at determining talent that makes it to the majors after 23.

Unranked offensive talent that made it to the majors by 22 had a surprisingly high success rate regardless of whether they went to college or not. So did unranked offensive talent that made it to the majors by 24 that went to college. This indicates that Baseball America could improve the accuracy of its projections by ranking more of these players.

Very few pitchers that made it to the majors that were 24 or older were successful regardless of whether they went to college or not. Baseball America was able to predict only one successful pitcher in this age bracket roughly every three years from 1998-2006. 

The majority of successful prospects entered the majors by 22. This indicates that age is more than just a number. The earlier a player reaches the majors the better his chances of success. Age has a definite impact on prospect success rates.

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