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The Not-So-Secret Key to Prospect Evaluation

I bet you thought I'd never get around to finishing this series...

Statistical Prospect Evaluation Primer: Part 4

The title of this post is a bit of a misnomer; there is no secret to prospect evaluation. You need the input of (multiple) scouts, your own observations, and finally statistical evaluation like I've presented in this series.

But there was one aspect of prospect evaluation I purposefully left out of the first three parts, probably because it seems wholly obvious.


Each level of the minor leagues provides an ever increasing level of competition which acts as a giant filter for minor league clubs. For the most part, only those able to conquer A ball are allowed to advance to High-A, and those who conquer High-A allowed to advance to AA, and so on. This ensures only the cream of the crop even gets a shot at the major leagues.

Because each level provides an increased challenge, a prospect who maintains good production from year-to-year while advancing a level is often considered a good candidate for future major league success. But no prospect is perfect; they all have weaknesses, areas in which they can improve. And it's that improvement, that year-to-year improvement, that I love to find in a prospect.

I like to think of improvement, statistically observable tools progression, as the 6th tool. There is a large jump in competition between the majors and minor leagues, and a prospect who has demonstrated the ability to improve their game while in the minors (I believe) is more likely to be able to adjust to that jump in competition.

Put simply, I believe learning and adjustment is a skill. Some players have it, others don't.

After the jump, I take a look at the minor league careers of 4 current White Sox players to illustrate my point.

John Danks

John Danks' Minor League Career

Year Age Lev W L ERA G GS IP H R ER HR BB K WHIP H/9 BB/9 K/9 K/BB
2004 19 A 3 2 2.16 14 8 50 38 17 12 14 64 1.04 6.8 2.5 11.5 4.57
2004 19 A+ 1 4 5.24 13 13 55 62 38 32 26 48 1.60 10.1 4.3 7.9 1.85
2005 20 A+ 3 3 2.50 10 10 57.2 50 18 16 5 16 53 1.15 7.8 2.5 8.3 3.31
2005 20 AA 4 10 5.49 18 17 98.1 117 66 60 12 34 85 1.54 10.7 3.1 7.8 2.5
2006 21 AA 5 4 4.15 13 13 69.1 74 38 32 11 22 82 1.39 9.6 2.9 10.6 3.73
2006 21 AAA 4 5 4.33 14 13 70.2 67 43 34 11 34 72 1.43 8.5 4.3 9.2 2.12

John Danks minor league career provides a great illustration why you should ignore W-L record and ERA. He posted minor league career ERA of 4.20 with a dismal 21-30 record. If he can't even win minor league games or hold a bunch of wannabes to under 4 runs a game, how can possibly project him to have future major league success?

First, and maybe most importantly, he was exceptionally young for his league at every step. He also posted very good strikeout rates (9.3 K/9) and a K/BB ratio approaching our magic 3:1 at 2.80. But it's when you look more closely at Dank year-to-year and level-to-level progression that his improvement becomes apparent.

Danks received mid-season promotions every year in the minors, and almost always struggled with his control in his initial tour of a new level, only to show great improvement in a return trip to that level the following year. So while Danks didn't quite meet my magic 3:1 K/BB ratio for his minor league career, he always posted marks well above 3:1 on his return trip to a level. 

Danks demonstrated the ability to learn, to adapt at the minor league level all while being young for his league. Combined with the excellent scouting reports, Danks was exactly the type of pitcher you'd expect to be able to make the adjustments to make a successful jump to the majors, as we've seen first hand with his addition of the cutter.

Paul Konerko

Paul Konerko's Minor League Career

1994 18 A- 67 306 257 25 74 15 2 6 58 1 0 36 52 .288 .379 .432
1995 19 A+ 118 519 448 77 124 21 1 19 77 3 1 59 88 .277 .361 .455
1996 20 AA 133 557 470 78 141 23 2 29 86 1 3 72 85 .300 .397 .543
1997 21 AAA 130 560 483 97 156 31 1 37 127 2 3 64 61 .323 .407 .621
1998 22 AAA 63 275 237 41 82 18 0 14 65 1 0 30 30 .346 .415 .599

I almost feel guilty using Paul Konerko as an example in a piece like this. His pedigree as a top 10 pick and minor league career is that of a can't miss prospect, which is how he ended up ranked as the #2 prospect in all of baseball prior to the '98 season. But now that the White Sox have a number of legit prospects, this is the type of minor league career we're looking for.

Konerko began his minor league career as an 18 year old in short season ball, displaying a little power. His strikeout rate (17%) was a little high, but he was extremely young for his league. With a jump to high-A, an aggressive jump for a high-school draft pick, Konerko held his K-rate steady, flashed some more power and earned a promotion to AA the next year.

AA is often referred to as a litmus test for prospects, and Konerko passed with flying colors. He lowered his K-rate to 15%, raised his walk-rate to 13%, and upped his power yet again. And with his final full-season AAA, Konerko advanced even further. His cut his K-rate to under 11% and raised his walk rate to reach the magical 1:1 ratio. Oh, and he had 69 extra-base hits, including 37 HRs, although he was playing in one of minor league baseball's best hitter's parks. Konerko had advanced to become a darling of both scouts and stat-heads alike. 

Brian Anderson

Brian Anderson's Minor League Career

2004 22 A+ 69 283 254 43 81 22 4 8 46 10 1 29 44 .319 .389 .531
2004 22 AA 48 204 185 26 50 9 3 4 27 3 2 19 30 .270 .338 .416
2005 23 AAA 118 501 448 71 132 24 3 16 57 4 2 44 115 .295 .360 .469

Now that we've seen what a couple of high-first-round success stories look like, let's take a look another first rounder who hasn't quite fared as well. Brian Anderson was never my favorite prospect, but searching the archives here you'll probably find me ranking him ahead of Chris Young and Ryan Sweeney, both of whom I liked better (long-term) than Anderson. The reason being, Anderson appeared to do everything well, and while I never thought he would be an All-Star, I thought he would be an adequate major league regular. I was wrong. Let's see why.

In his first full season, Anderson was assigned to high-A, which is the safe choice for your first-round collegiate picks. Anderson performed exactly how you'd expect from a blue chip prospect, posting solid walk (>10%) and strikeout rates (~15%), and earned a mid-season promotion to Birmingham. While Anderson's average and ISO took a bit of a hit after the promotion, his strike zone control remained good, or at least consistently adequate.

A year later at AAA, Anderson's OPS rebounded above his AA levels, but there was a great big ole warning sign in the form of a drastically increased strikeout rate, now around 22%. I was fooled. I saw an .800+ OPS from a plus-defensive CF, and figured he could easily replace the .736 Aaron Rowand provided in '05. And if he couldn't, I figured Young, who I liked better, but was not without flaws, would be ready to take his place for '07. 

What I missed, or rather what Anderson never demonstrated over the course of his minor league career, was an ability to adjust to a jump in competition level, to learn from his failure. The Brian Anderson who broke camp with the '09 White Sox remains very much the same one the White Sox drafted in '03. I've never trusted a prospect who didn't show me some improvement since.

Chris Getz

Chris Getz' Minor League Career

2005 21 A 55 253 214 38 65 13 2 1 28 11 4 35 10 .304 .407 .397
2006 22 AA 130 573 508 67 130 15 6 2 36 19 6 52 47 .256 .326 .321
2007 23 AA 72 319 278 40 83 10 2 3 29 13 7 36 30 .299 .382 .381
2008 24 AAA 111 457 404 60 122 24 1 11 52 11 4 41 53 .302 .366 .448

Finally, we get to the long awaited reasoning behind my confidence in Chris Getz. He received an aggressive assignment to A-ball as a 4th round draft-pick, where Getz quickly proved he had an advanced approach at the plate posting a 10/35 K/BB ratio.The Sox took notice and skipped him over high-A (where you often see college first rounders sent) to AA in his first full-season.

Getz would struggle to hit the ball with any authority in Birmingham's expansive outfield, but still demonstrated excellent strike zone control with more walks than strikeouts. He returned to Birmingham the next season, and immediately showed better results at the plate while maintaining his positive plate approach. He would have been a candidate for a mid-season promotion, but injury would delay his AAA debut for another year. 

Last season in AAA, Getz saw his K/BB numbers continue to trend in the wrong direction. But at 53/41 in 457 plate appearances, his K-rate remains well under the 15% danger zone and his BB-rate is close to 10%, .

The move to Charlotte's smaller ballpark also helped in the ISO category, as Getz saw a large spike in the HR and XBH categories. Though it's unclear how much of that spike can be attributed to a hitter-friendly ballpark.

Getz is far from a sure thing as a prospect, and his K and BB rates have actually trended in the wrong direction as he climbed the minor league ladder. But his rebound performance in AA, increased ISO in AAA, and K/BB ratio near 1:1 led me to believe he was the White Sox' best 2B candidate in February. And while he doesn't figure to be a star, his advanced approach at the plate and propensity to do of the little things leaves him in a good position to provide quaility at-bats for the Sox in the short term with a fall back of grindy utility player in the long-term.

There is still one last piece in this series which will highlight what we should be watching for in the box scores of current White Sox prospects. Both Jim and Larry have briefly covered this, but I'd like to have a more comprehensive list/post. Hopefully it will find its way to the blog in the next month, probably on an off-day like today.