This idea comes courtesy of a tweet from Adam Foster of ProjectProspect.com:
MiLB ground ball rates continue to be a widely overlooked part of pitching prospect evaluation.
Low GB% can be an indicator of pitchers who take advantage of MiLBers by overpowering them with high FBs, which rarely works in the bigs.
This makes quite a bit of sense, and could explain why so many highly regarded pitching prospects are struggling in 2012. Let's take a look at some numbers after the jump to drive this point home...
We'll examine three pitching prospects, (Julio Teheran, Shelby Miller, and Dellin Betances) who are struggling mightily this year after having moments of brilliance in the lower minors in the past.
Julio Teheran - Braves
| Year | Level | GB % | FIP |
| 2009 | A | 49 % | 3.96 |
| 2010 | A | 46 % | 2.70 |
| 2010 | A+ | 42 % | 3.11 |
| 2010 | AA | 38 % | 3.47 |
| 2011 | AAA | 41 % | 3.10 |
| 2011 | MLB | 28 % | 5.84 |
| 2012 | MLB | 9 % | 1.51 |
| 2012 | AAA | 35 % | 5.35 |
Shelby Miller - Cardinals
| Year | Level | GB % | FIP |
| 2009 | A | 55 % | 4.25 |
| 2010 | A | 46 % | 2.87 |
| 2011 | A+ | 36 % | 2.01 |
| 2011 | AA | 45 % | 2.91 |
| 2012 | AAA | 34 % | 5.36 |
Dellin Betances - Yankees
| Year | Level | GB % | FIP |
| 2009 | A+ | 51 % | 3.73 |
| 2010 | A+ | 43 % | 2.06 |
| 2010 | AA | 25 % | 4.13 |
| 2011 | AA | 51% | 3.93 |
| 2011 | AAA | 31 % | 4.19 |
| 2011 | MLB | 14 % | 9.43 |
| 2012 | AAA | 42 % | 5.87 |
| 2012 | AA | 40 % | 3.64 |
Other than the fluky MLB total for Teheran this year, there appears to be some legs to the use of minor league ground ball rates as a progress indicator. Teheran and Betances are very similar, in the sense that both have a tendency to keep the ball up in the zone, and higher level hitters have punished them mightily. Miller has been far too reliant on his fastball this year, so much so that the Cardinals have him on a strict "no shake" rule, and are calling pitches for him.
A perfect example of strong minor league ground ball rates translating to major league success is Ivan Nova, who we're all very familiar with. A 2012 prospect example would be Mets pitcher Matt Harvey, who has seen his groundball tendencies carry over from the upper minors, and have been a driving force behind his early major league success.
Matt Harvey - Mets
| Year | Level | GB % | FIP |
| 2011 | A+ | 51 % | 2.85 |
| 2011 | AA | 51 % | 3.46 |
| 2012 | AAA | 46 % | 3.69 |
| 2012 | MLB | 43 % | 4.16 |
This is good news for Manny Banuelos, who has traditionally displayed strong groundball rates during his minor league career (50% in '11, 43% in '12), and also Jose Campos (51% in '11, 45% in '12). Get well soon, boys.
This could also explain the immediate success of David Phelps this season (40% at AAA in '11, 43% with Yankees in '12). While Nova and Phelps were never stud prospects, both have shown the necessary skills needed to successfully navigate major league lineups.
Take what you will from this. I thought it was interesting, and something that may possibly shed light on how future Yankees pitching prospects eventually translate to the major leagues.