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Prospect Coverage at TGP: A Primer

Let's get this out of the way first: analyzing prospects isn't an exact science.  Beau Hale was drafted a pick before Chase Utley, Kevin Youkilis never made a Baseball America Top 100 list, and Ben Grieve was projected to be one of the better hitters of all time.  That all looks crazy from our current vantage point, but that's just the way it goes: sometimes can't miss guys fail, and sometimes a 13th round pick becomes the best player in baseball.

But the uncertainty involved shouldn't stop us from trying.  One look at the WFC 2008 Philadelphia Phillies, and their homegrown core of Chase Utley, Cole Hamels, Ryan Howard, and Jimmy Rollins, shows just how important prospects can be.

For our purposes here at The Good Phight, analyzing prospects is a two-part exercise:

  1. Reading scouting reports
  2. Analyzing statistics

Simple, right?  Well, not completely.  Between Baseball America, Kevin Goldstein at Baseball Prospectus, John Sickels, Keith Law, and some others, there's a lot more scouting info out there on prospects than there used to be.  Still, in-season updates are often tough to come by, so a bit of mixing and matching is required to fulfill the first part of the above equation.

Then, of course, there's the process of weighing those scouting reports against the available statistics -- how much emphasis should we assign to each?  Contrary to the oversimplified understanding of Moneyball, we can't simply ignore scouting reports altogether and focus on statistics.  But neither can we ignore statistics, because they obviously play a crucial role in the equation -- as long as we know which statistics to look at.  So let's go ahead and highlight some of the statistical categories we'll be focusing on when we evaluate prospects, and why they're useful.


Hitting Statistics

BA/OBP/SLG: Batting average, on base percentage, and slugging percentage.  Referred to as a hitter's "triple slash line," and expressed in that manner (e.g. in 2009, Tyson Gillies hit .341/.430/.486).  Serves as a concise representation of a player's all-around performance at the plate.

K%: Strikeout percentage.  Calculated by dividing the number of strikeouts by the number of plate appearances (K% = K/PA).  Can be a useful proxy for assessing a hitter's contact abilities.  Anything below 10% is outstanding; anything above 25% is a major red flag; and in-between numbers need to be judged in combination with BB% and ISO (see below).

BB%: Walk percentage.  Calculated by dividing the number of walks by the number of plate appearances (BB% = BB/PA).  Shows a hitter's patience at the plate.  Anything above 15% is outstanding; anything above 10% is good; anything below 7% or so is a major red flag.  Should be assessed in conjunction with K% and ISO (see below).

ISO: Isolated power.  Calculated by subtracting batting average from slugging percentage (ISO = SLG - BA).  Basically demonstrates how much power a hitter has.

As alluded to above, a particularly useful exercise is to compare the above three statistics -- K%, BB%, and ISO -- to each other in order to assess a hitter.  Generally speaking, a good prospect should be average to above-average in at least 2 of the 3 categories.  Let's march through a couple of examples.  Yankees prospect Jesus Montero only walked in 7.4% of his plate appearances in 2009, but should still be an excellent hitter because of an impressive combination of power (.225 ISO) and contact ability (13.5% K).  Indians prospect Michael Brantley routinely posts subpar ISOs (e.g. his .094 mark in Triple-A in 2009), but he can get away with it because he controls the strike zone extremely well (with an 11.4% BB and a 10.5% K).  Finally, Marlins prospect Mike Stanton had trouble with strikeouts this year (30.1% K), but walked a decent amount (10.7% BB) and absolutely crushed the ball on contact (.246 ISO).

We'll continue to discuss these three statistics in relation to each other as we analyze the Phillies prospects.  It's by no means a hard and fast rule, especially given the importance of scouting reports, but it often serves as a useful starting point for assessing a hitter's potential going forward.

wRC+: League and park adjusted runs created based on weighted on base average (wOBA). This isn't nearly as complicated as it sounds -- we can basically think of it as a version of OPS+ that is available for minor leaguers.  It is based on an average score of 100.  To illustrate: Domonic Brown's 156 wRC+ in Clearwater in 2009 made him 56% better than league average hitter.  Two important notes: wRC+ takes into account stolen bases (and caught stealings); and it is already league and park adjusted, so we wouldn't say that Brown's 156 wRC+ was more impressive because it was in the FSL, because it's calculated relative to that league.

Pitching Statistics

FIP: Fielding independent pitching. Calculated using only the defense-independent elements of strikeouts, walks, and home runs surrendered (see here for the detailed formula). FIP is superior to ERA because it removes much of the element of luck -- i.e. the strength or weakness of a pitcher's fielders -- from assessing a pitcher's performance and ability.

K/9: Strikeouts per 9 innings.  Perhaps the most important statistic for a pitcher in the minors, because it has the highest correlation to future major league success.

BB/9: Walks per 9 innings.  Shows a pitcher's control (i.e. his ability to throw strikes), if not necessarily his command (i.e. his ability to put a pitch exactly where he wants it).

HR/9: Home runs per 9 innings.  The third of the "three true outcomes" over which a pitcher has a large measure of control (along with strikeouts and walks).  Can be useful in assessing a pitcher's command; Carlos Carrasco, for instance, posted a 2.99 BB/9 in 2009, but his 1.10 HR/9 could indicate that he's catching the fat part of the plate too much with his pitches.

GB%: Ground ball percentage. Calculated as a ratio of grounders to other balls in play.  Batted ball data tends to be unreliable for the minor leagues (specifically in differentiating between fly balls and line drives), but ground ball data is accurate and useful.  Generally speaking, the higher the ground ball percentage, the better, because ground balls tend not to turn into extra base hits and home runs.

Other Statistics

Spd: Speed score.  Originally invented by Bill James, the speed score utilized by Fangraphs is calculated using four components: stolen base percentage, frequency of stolen base attempts, percentage of triples, and runs scored percentage.  It generally ranges from 0 (slowest) to 10 (fastest), and serves as a more accurate guide of a player's speed than his stolen base totals.  In the absence of reliable fielding metrics for the minor leagues, it can also be useful in assessing a fielder's range, particularly for outfielders.

TotalZone: An advanced defensive metric akin to UZR or Plus/Minus, TotalZone data is available on the individual player pages of Minor League Splits.  Given the unreliability of batted ball data for the minor leagues, TotalZone figures should be utilized cautiously, and ideally in multi-year sample sizes in conjunction with scouting reports.


Finally, a word about the structure of the Phillies' farm system.  Most baseball fans are familiar with the general concepts (Triple-A is closest to the majors, etc.), but each league has its nuances, so I thought it might be useful for a rundown of the organization's affiliates.

Lehigh Valley IronPigs (Triple-A International League): There isn't really much to say here, to be honest.  Triple-A is obviously just below the majors, and generally speaking, guys who can produce here will be able to contribute to some degree at the major league level.  Coca-Cola Park plays pretty neutral.

Reading Phillies (Double-A Eastern League): The jump to Double-A is widely considered the toughest in the minors, and for good reason: it's generally where pitchers with middling stuff (but good command) get exposed by more patient hitters, and where impatient hitters see their plate discipline collapse due to facing better pitchers.  It's also the first level on the way up the chain where you see a lot of minor league lifers, whose steady play establishes a base level of performance that contributes to the whole "weeding out" process of guys making the jump from A-ball.  An additional point to consider when assessing R-Philsstatistics: FirstEnergy Stadium is a bit like a mini Citizens Bank, in that it doesn't necessarily boost offense as a whole, but it has quite the effect on home run totals.

Clearwater Threshers (High-A Florida State League): High-A is where the majority of college draftees (or, at least, the real "prospects" among college draftees) begin their first full pro season.  The FSL is known for being a pitcher's haven: the stadiums are large, and the mid-summer air is very humid, which tends to keep balls in the park.  Bright House Field is not quite as expansive as some of the other FSL parks, but pitcher and hitter numbers for Threshers players should still be judged with the pitching-friendly slant in mind.

Lakewood BlueClaws (Low-A South Atlantic League): The SAL is where some of the more advanced high school draftees will start their first full pro season, along with the lesser college players.  It's the lowest of the full season league teams, so anyone not making the BlueClaws roster will stay in extended spring training, then head to either Williamsport or the Gulf Coast League when those seasons start up.  Lakewood's FirstEnergy Park (ironically, as opposed to Reading's FirstEnergy Stadium) plays very large, severely suppressing home runs but surrendering a tad more in the way of doubles.

Williamsport Crosscutters (Short Season New York-Penn League): The highest level short season league, the NYPL is another pitcher's haven, as it's generally populated by college pitching draftees (often senior signs) who are simply too much to handle for many 19- and 20-year old hitters, and for many college hitters trying to adjust to wood bats.  As if that's not enough, Bowman Field -- trivia: the second oldest minor league park in the country -- is quite large, and plays as a pitcher's park even within the context of the already pitcher-friendly NYPL.

Gulf Coast League Phillies (Short Season Gulf Coast League): The lowest affiliated level in the U.S., the GCL is yet another pitcher-friendly league for the same reasons as the FSL.  The GCL is generally populated by a mix of recent high school draftees, international signees whose performance warranted a promotion from the foreign domestic leagues, and a handful of college and juco draftees who can't fit on the Williamsport roster.  The GCL is basically an instructional league, so the statistics need to be taken with a large grain of salt, especially for high schoolers drafted that June who may be struggling to make the initial adjustment to pro ball.

Beneath the GCL Phillies are the academy clubs run by the organization in the Dominican Summer League and the Venezuelan Summer League.  While the higher-priced international signings like Domingo Santana and Freddy Galvis will generally debut in the GCL, lower level signings like Jonathan Villan and Leandro Castro must prove themselves before meriting promotion to the U.S.