The following series will count down the 25 highest ceilings (based on AOFP grades) in the Rangers' minor league system. I have scouted every player on the list in person and compiled the grades using those observations, conversations with respected voices in the Rangers' community like Lone Star Dugout's Jason Cole, and conversations with numerous scouts. Being a subjective exercise, opinions will vary on the individual tool grades, and ultimately, on the final tool projections.
Before we discuss the scouting scale and my methods of evaluation, it's important to note that the AOFP-based rankings below differ from the prospect rankings you may be more accustomed to seeing. The grades here are based on raw tools, and aren't intended to capture each player's most realistic ceiling. Age, league, and other contextual factors are generally excluded, although younger players have more room for development and therefore can receive the benefit of such an abstract view.
It should also be noted that this series was designed to highlight players currently playing in the Rangers' minor league system. For example: a player like Neftali Feliz, whose composite grades would rank him in the top tier of prospects in the system, will be excluded from this list because he is currently on the 25-man roster and not likely to spend any time on the farm.
The Scouting Scale/Methods:
For each tool (hitter) or individual offering (pitcher), a scout assigns the player a grade on a numerical scale that runs from 20 to 80 in five-point increments. 50 is major-league average, and 80 represents the top available score. The sides of the tool bell curve are extremely steep, and there's not much space beneath the curve's tails. In other words, there are very, very few players with 80-caliber tools, and lots of prospects whose tools score a 50. Because of this, scouts may also assign qualitative descriptors (e.g., "fringe-average," "solid-average") to modify scores of 50 that don't quite warrant a bump down to 45 or up to 55.
The scout averages the tool grades to produce an "Overall Future Potential" (OFP) grade. (As a result, OFP also has a 20-to-80 range, but isn't limited to scores ending in "5" or "0.") After OFP is calculated, a scout can adjust it based on his observation, experience, and intuition. This results in an AOFP: the "A" stands for "adjusted." An AOFP above 60 is generally indicative of an elite prospect: a guy with the potential to star in a championship-caliber lineup, rotation, or bullpen.
An AOFP of 55-59 typically implies a prospect that will be a first-division starter, including a solid No. 2 or No. 3 starter, front-line reliever, or second-tier closer. AOFPs in the 50-54 range suggest a solid-average major leaguer, including back-of-the-rotation starters and some late-inning arms who fall just below having "front-line" status. Players with AOFPs lower than 50 are usually fringe-average players like utility infielders, fourth/fifth outfielders, and middle relievers. Not a single player on this list will have an AOFP below 54.
Name: Robbie Erlin
Birthplace: Santa Cruz, CA
HT/WT: 5' 11", 175 lb.
Arm action: Very good
Delivery/Mechanical characteristics: Good; clean and repeatable; hides ball well; high three-quarters delivery
Physical description: Short and athletic with strength; lacks physical projection
Abilities: Advanced pitchability and mound maturity for his age. Good FB velocity for LHP, with solid natural weight and run. Movement and location push the pitch to the fringe-plus level. Despite height, is able to generate good angle on the FB. Delivery is smooth with long stride and late hand-break. CB is his best offering, thrown in the 75-78 range with two-plane break. The pitch is tough on LH and RH alike because of it plays well off his FB, offering deception, and has 11/5 (1/7) shape. CU is a potential solid-average pitch with arm-side fading action and the same natural weight as his sinking fastball. The pitch will flash plus at times, and could exceed projection and become true plus pitch. Athleticism and repeatable keep his release points consistent and allows for above-average command/control projection. Shows above-average feel for pitch sequence and situation, with ability to throw all three pitches to LH/RH. Fields position well.
Weaknesses: Lacks elite arsenal and prototypical size for a starter. When he doesn’t stay on top of his FB, the pitch tends to flat-plane and elevate, either catching too much of the upper zone or missing high. CB can get to loopy when it’s soft-tossed, causing a loose rotation and early break. CU is still a developing pitch with some arm speed inconsistencies causing the pitch to float and not tumble. Needs to sharpen his command within the zone; comes across body some. Hasn’t worked in a rotation as a professional, so sustainable velocity/stuff a question mark until it isn’t one.
Conclusion: Lowered OFP one point based on non-elite overall arsenal and lack of physical projection. Erlin has solid-average or better projections across the board, with solid pitchability and plus make-up/work ethic.. His FB has some natural sink to it and his command/control projections are above-average. His CB is a money pitch with a tight rotation and sharp two-plane break. His CU has solid-average projection giving him a third quality pitch. Tool-based grade: 56; solid-average No. 3 starter at the major league level.