Players moving between AAA and Majors

So, looking back at the question of the 3A to majors conversion.

First, these differences are almost certainly an overstatement of the difficulty distance between the 2 levels. There is a pretty substantial selection bias working in both directions:

• players in 3A who by chance are performing above their real talent level are more likely to get promoted to the majors
• Major league players underperforming by chance are more likely to be sent down to 3A
• Either way, when they revert to their real talent level, it will make the gap look bigger

OK, first question – what is the baseline change for players moving between 3A and the majors in the same year?

I am going to use my “nodif” translations – this eans I am only translating for the park factor and the league offense level. There are no adjustments for league quality or player age. I looked at all players from 2001-2025 who had at least 50 PA at both levels. Players on multiple teams at those levels have their statistics combined. Stats for a player are weighted to the lesser PA value – someone with 98 PA in 3A and 371 major league PA would only credited with 98 PA in both the 3A and major league summations.

There were 3631 matched pairs over 25 (really 24, no 2020) years,which works out to an average of 5 players per team per year.

         AB             H         DB        TP         HR    BB      SO        SB        CS    BA  OBA S LG  EQA   EQR

3A 374279 105499 19758 2844 14751 38666 72995 9433 3570 .282 .349 .468 .285 58466

MJ 380494  92268 15874 2354 10157 32451 90412 6376 2709 .242 .302 .377 .243 42131

The baseline difference for 2001-2015 is 42 points of EQA.

Second question – has that changed over time?

Let’s break those players above into 5-year blocks:

Delta            BA OBA SLG EQA

2001-2005  -41  -51   -95  -46

2006-2010  -40  -49   -90  -43

2011-2015  -39  -46   -86  -41

2016-2019  -37  -43   -86  -39

2021-2025  -40  -46   -99  -43

It appears that there was trend towards a narrowing of the difference between 3A and the majors, at least up until the covid year of 2020. The gap between 3A and the majors – at least in terms of same-year transitions – is essentially unchanged since 2006. You could say that it has gotten little more difficult in recent years, especially compared to the 2010s.

Number three – does age matter?

Maybe a little bit

Delta      BA OBA SLG EQA

age 20 n=19 -23 -32 -64 -30

age 21 n=81 -37 -44 -90 -40

age 22 n=194 -41 -46 -98 -42

age 23 n=365 -33 -40 -77 -36

age 24 n=493 -39 -48 -88 -41

age 25 n=541 -42 -50 -99 -45

age 26 n=486 -40 -47 -94 -43

age 27 n=397 -45 -52 -104 -48

age 28 n=284 -39 -45 -89 -41

age 29 n=240 -40 -48 -96 -44

age 30 n=149 -38 -49 -85 -40

age 31 n=118 -42 -53 -91 -46

age 32 n=90 -40 -47 -87 -41

age 33 n=77 -34 -39 -85 -36

There is a small tendency for young players to do a little better than older players.

Next question – does a start like Caglianone or Holliday has had doom their career?

Jac Caglianone is sitting on a -183 – a .348 EQA in Omaha and a .165 mark in Kansas City. That is the 57^th worst entry in the list of 3634 – that is in the 2^nd percentile.

Jackson Holliday went from a .312 in Norfolk to .219 in Baltimore last year, a -93 mark that puts him in the 16^th percentile.

The absolute worst performance appears to be from Skye Bolt, who had a rousing .362 EqA at Las Vegas in 2021 (a real-life .387/.492/.650 line) that turned into a major league 5-57 line with exactly one double, home run, and walk to go with it – that goes for a .000 EqA, so -362.

Looking just at 21-23 year olds…

Ben Zobrist had a pair of disastrous major league promotions – going from .282 to .191 in 2006 and an even worse .308 to .104 in 2007. He proceeded to hit for .285 EqA over the next 10 years, very much in keeping with his overall minor league performance.

Kyle Tucker in 2018 had a .139 EqA in Houston after a .320 In Fresno. He’s done alright since.

Kolten Wong’s debut was .115 after .288, in 2013, and had a solid career.

Hunter Renfroe had a -179 in 2017, but that was mostly the result of a ridiculous .434 EqA at triple-A. His major league performance was a perfectly acceptable .255, which he bettered over the next 5 years.

Andy Marte, though, in 2005. His failure in Atlanta (.150 EqA after a .292 in Richmond) well foretold a career .290/.217 minor/major split.

Byron Buxton hit just .206 in his major league debut. Anthony Rizzo started at .200. Adam Jones had a .177.

And I would be remiss not to mention Dustin Pedroia’s 2006, hitting just .178 in Boston after dazzling Pawtucket with a .290.

But it isn’t all good. Marte, I already mentioned. Jarred Kelenic is on the list. Chad Hermansen. Hanser Alberto. Jack Kroeger. Garrett Atkins. Brett Carroll. Aaron Cunningham. Lots of forgettable players among the ones who turned out fine.

But, clearly, it is recoverable.

Last question – do some teams do better or worse than others?

Here is the average EqA drop, from 3A to Majors, broken down by team, for 2021-2025.

The Blue Jays show as the best team in baseball recently, with multiple players doing better in the majors than triple-A (Joey Loperfido and Davis Schneider this year, Nathan Lukes last year, Schneider again in 2023, Cavan Biggio in 2021)

The Brewers’ score is far more flukey, depending on huge “improvements” from two players who actually did rather poorly in the majors, but were even worse in 3A – Daniel Robertson in 2021 and Mike Brosseau in 2023.

Surprising to see Miami near the top, given how bad they’ve generally been and the high volume they go through.

The bottom four teams are a fascinating mix of two very bad franchises with high volume and two very good franchises with low volume.