Nearly Ready? A Look at AAA Pitchers

Baseball fans like to know what’s happening with minor leaguers in their favorite team’s farm system. Rabid baseball fans follow all the key prospects in baseball at any given time. Since we’re through six weeks of minor league baseball, we’ve got fair-sized chunks of data to peruse.

This first report will focus on pitching prospects plying their trade in AAA — the highest level of the minor leagues. Since most major league teams suffer injuries to their pitchers as the season progresses, there will likely be a need to bring pitching up from AAA. As such, there’s a lot of interest in how their most senior prospects are doing.

I’ve selected starting pitchers who have faced 100 batters or more in AAA and who will be under 26 years of age as of July 1, 2004. Surprisingly, only 65 pitchers — just over two per organization — make the cut. Many of the other AAA starters are veteran roster fillers.

The first thing I want to know about a pitching prospect is his strikeout rate. Strikeouts are an indicator of pitching dominance, and there are few things teams get more excited about than a pitcher who dominates with the hard stuff. Strikeout pitchers are less reliant on the defense behind them, and have been shown to have longer careers than finesse (low-K) pitchers.

The most popular measure of dominance is strikeouts per nine innings pitched, but it’s not the one I like best. Each batter a pitcher faces is a potential strikeout victim and a pitcher who strikes out three straight batters has shown more dominance than one who strikes out three batters, but also gives it walk, a home run and hits a batter. I will therefore list the 10 best in each league in K percentage — strikeouts per opportunity (PA-IBB). You’ll notice that I exclude intentional walks (which are thankfully rare in minor league baseball) because they are more a reflection of managerial strategy than of pitching ability.

Notes: All stats as of May 17th, 2004. They are not park-adjusted.

Strikeout Percentage
International Org Age K percent Pacific Coast Org Age K percent
Brandon Claussen CIN 25.2 26.1 Danny Haren STL 23.8 31.7
Jorge De La Rosa MIL 23.2 22.0 Joel Hanrahan LA 22.7 22.8
Aaron Heilman NYM 25.6 21.8 Juan Dominguez TEX 24.1 22.5
Felix Diaz CWS 23.9 21.3 Adam Wainwright STL 22.8 22.2
David Bush TOR 24.6 21.1 Jon Leicester CHC 25.4 22.0
Jung Bong CIN 24.0 20.7 Clint Nageotte SEA 23.7 20.1
Jon Rauch CWS 25.8 20.0 Mike Nannini FLA 23.9 19.5
Matt Guerrier MIN 25.9 19.9 Zack Greinke KCR 20.7 19.3
Willie Eyre MIN 25.9 19.6 Dave Williams PIT 25.3 18.6
Andy Van Hekken DET 24.9 18.5 Cha Seung Baek SEA 24.1 18.6
League     18.4       17.0

Having a great fastball and off-speed stuff isn’t enough; you’ve got to have command of it. The measure I use is non-intentional walks per opportunity, eliminating hit batsmen from opportunity.

Non-Intentional Walk Percentage
International Org Age NIW percent Pacific Coast Org Age NIW percent
Matt Guerrier MIN 25.9 2.1 Heath Totten LA 25.8 2.5
Dave Gassner MIN 25.5 3.2 Mike Ziegler OAK 24.9 3.6
Josh Stevens BOS 25.1 3.3 Cha Seung Baek SEA 24.1 3.9
Felix Diaz CWS 23.9 3.3 Aaron Cook COL 25.4 4.6
Shane Loux DET 24.8 4.2 Dave Williams PIT 25.3 4.7
Andy Van Hekken DET 24.9 4.5 Zach Greinke KCR 20.7 5.1
Matt Belisle CIN 24.1 4.7 Cory Vance TEX 25.0 5.5
David Bush TOR 24.6 5.3 Sean Burnett PIT 21.8 5.9
Joe Valentine CIN 24.5 5.5 Chadd Qualls HOU 25.9 6.0
Brad Halsey NYY 23.4 6.4 Mike Wood OAK 24.2 6.1
League     7.9       8.7

Finally, a measure of overall effectiveness: My choice is a modified version of FIP (Fielder-Independent Pitching, developed by Tangotiger) which excludes intentional walks, but includes hit batsmen. FIP is a close cousin of DIPS (developed by Voros McCracken). The advantage of FIP over DIPS is that is is very easy to calculate (see formula in caption).

What DIPS and FIP aim at is to eliminate much of the influence of fielding, while retaining much of the pitcher’s contribution. This makes either measure a better choice than straight ERA or runs allowed per 9 IP, both of which are heavily influenced by the fielders.

Home runs allowed is a volatile stat which is greatly affected by small sample size, park and opposition batters (moreso than strikeouts and walks). Because home runs carry so much weight in FIP, pitchers allowing a cluster of home runs (such as Dodgers prospect Joel Hanrahan) will be severely punished, while others who have not contracted gopheritis will thrive. The reader is reminded that these figures are not park-adjusted.

Modified FIP [ (13*HR+3*(W-IW+HBP)-2*K)/IP+3 ]
International Org Age mFIP Pacific Coast Org Age mFIP
Dewon Brazelton TBD 24.0 2.73 Joe Blanton OAK 23.6 2.62
Felix Diaz CWS 23.9 2.75 Sean Burnett PIT 21.8 2.63
David Bush TOR 24.6 2.85 Aaron Cook COL 25.4 2.91
Shane Loux DET 24.8 2.89 Mike Ziegler OAK 24.9 3.08
Ben Hendrickson MIL 23.4 3.05 Zach Greinke KCR 20.7 3.14
Matt Belisle CIN 24.1 3.16 Juan Dominguez TEX 24.1 3.15
Brad Halsey NYY 23.4 3.19 Dave Williams PIT 25.3 3.22
Dave Gassner MIN 25.5 3.27 Chad Qualls HOU 25.9 3.29
Andy Van Hekken DET 24.9 3.42 Adam Wainwright STL 22.8 3.46
Willie Eyre MIN 25.9 3.43 Dennis Tankersley SD 25.4 3.59
League     4.04       4.23

Joe Blanton, part of the famous “Moneyball” draft, looks to be following in the footsteps of the big three (Hudson, Zito, Mulder) that form the nucleus of the Athletics pitching staff. The A’s will be happy to keep Blanton in AAA for the first half of the season, as there isn’t much room in the rotation right now. If everyone continues to throw well, having six quality starters is a nice problem to have.

On the rise with a bullet is phenom Zach Greinke. With all the Royals’ rotation problems, the only thing keeping Zach in AAA is the service-time issue. The first week of June should be safe from that standpoint; look for Greinke to be in the rotation by then.

The Cardinals have two stud pitching prospects knocking on the door — either Danny Haren or Adam Wainwright will be fighting it out if/when the next St. Louis starting pitcher goes down to injury. David Bush is now a serious threat for the Blue Jays rotation if Pat Hentgen fails to add some MPH to his fastball.

Jorge De La Rosa (Boston-to-Arizona-to-Milwaukee), traded twice this off-season, has shown poor control to go with his high strikeout rate. I like what Juan Dominguez showed me in his brief stint with Texas last year. He’s a good candidate to replace R.A. Dickey in the Rangers rotation, but teams that are winning are usually reluctant to replace a starter unless he’s injured.

Edwin Jackson didn’t make any of these lists (16.2% K, 10.3% W, 3.85 mFIP). Evidently he needs more polish and at 20 years of age, there’s no rush. Sean Burnett is only a year older, and has more than held his own in the PCL. The danger is that the Pirates will bring Burnett up prematurely when they fade out of the NL Central race. Aaron Heilman (Mets), Jung Bong (CIN) and Brandon Claussen (CIN) are guys who’ve seen the bigs and will be returning there soon.

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