College Baseball Equivalencies

This is a project I've been working on and off for several months now. I plan to delve into these results much more in-depth and expand the sample size but I decided to post my preliminary results here for everyone to see.

Basically what I did was take the top 75 offensive college players who were drafted and played rookie ball in 2009. I weighted their stats by the lowest PA total (in college or in RK) for all players. Once the PA were equal I compared all the college numbers to the RK league numbers and created factors, which we will call Rookie League Equivalencies (RKLE).

The factors can be applied to a player's adjusted college stats to give a rough projection of how he will perform in Rookie-ball.

The factors are as follows:

.HR- .48

2b- .80

3b- .89

BB%- .88

HBP- .73

K%- 1.32

sb- .93

ISO- .59

wOBA- .85

The key stats I put in bold. As I had hypothesized walks carry over pretty highly. Strikeouts are likely to increase, so a player who strikes out a lot in college will strike out even more in the low levels of the minors.

Obviously one season of players is not a huge sample size and I will ideally add to this database. I also plan to expand to Low-A and other levels if there are large enough samples

Pawtucket Red Sox MLE

For the past few weeks I have been undergoing a project to convert the Major League Equivalencies of the Pawtucket Red Sox.

To do this I have gathered a database of all players who have played for Pawtucket and then in the major leagues since 1990. I found 48 such players. I compiled all of their numbers from Pawtucket as well as their career stats in the MLB. To adjust for the differences in plate appearances I scaled everything down to the fewer number of PAs (whether that be in Triple-A or MLB) and went from there. After adjusting for PAs I divided the minor league data set by the major league data set and found the factors. After some tinkering I reduced the number of hits, extra base hits, walks, and sac flies by 12%.

Now obviously this method has some flaws. The data is not park of age adjusted and the sample size could be larger. However, when checking my data against the MLEs used by www.minorleaguesplits.com they are very similar.

Here are my MLE conversion factors:

AB	R	H	1B	2B	3B	HR	RBI	SB	CS	BB	K	GDP	HBP	SF
1.016	.812	.857	.845	.898	.988	.820	.816	.688	.815	.748	.074	.865	.656	.966

And here are the numbers for the Pawtucket Red Sox. Their actual AAA numbers are on top and the raw MLEs are below that.

Spreadsheet

I am beginning to work on the pitchers, which I will hopefully have completed by next week.