Scouts evaluate the 5 tools a player possesses and assign a numeric grade for each tool. For position players, the tools are very well defined, and the importance varies based on the player’s position. The 5 tools for hitters are:

Hit For Average – self explanatory…the ability to make consistent contact
Hit For Power – self explanatory…the ball goes far when a player hits it
Defense – fielding ability and instincts
Arm – strength and accuracy
Speed – how fast/slow a player is, as well as ability to utilize the speed in games

For pitchers, the tools are a bit more ambiguous, but generally considered:

Arm Strength – fastball velocity…the more the better
Athleticism – being athletic makes it easier to repeat one’s delivery, which improves control/command
Secondary Pitches – you can’t live on a fastball alone at the major league level

Scouts rate tools on the 20-80 scale or the 2-8 scale. Baseball tools, like life, tend to fall on a Bell Curve. The majority of players will be grouped toward the middle (50) and then as you move away from the center (deviations), the frequency drops. Its beneficial to grade tougher, as the reality of the prospect game is that most prospects aren’t going to reach their absolute potential.

In addition to individual tools grades, scouts also give a player a OFP grade, or “overall future projection”, which is the player’s potential when he’s fully developed, healthy, and at his peak. Some guys take longer to get there, some guys never get there, and some guys get there right away. That’s baseball.

Here is an explanation of the 20-80 scale and how I will use it here

80 = Elite – Top of the charts. There are very few 80 tools in baseball. Mike Stanton’s power. Stephen Strasburg’s fastball. Michael Bourn’s speed.
70 = Well Above Average – Not quite amazingness, but really awesome.
60 = Above Average – Think all-star caliber
50 = Average – Just what it says. A perfectly average MLB player with all 50 tools would fit here. MLB average is actually valuable
40 = Below Average – Just what it says. You wouldn’t label a 40 tool as an asset, and a 40 overall player would likely be a bench player/Triple A guy who moves up and down
30 = Well Below Average – This individual tool would be a liability, and a 30 player is a AAA guy who might get a cup of coffee, but is never likely to play a meaningful role.
20 = Awful – Bottom of the charts. There are very few 20 tools, but more than 80s. Bengie Molina’s speed and Juan Pierre’s power are both 20 tools. A 20 overall player likely never gets past AA.

The importance of each tool varies by position.

For middle infielders, catchers and a center fielder, defense ranks much higher than for a left fielder or first baseman. For first basemen and left fielders, hitting for average and power are of the utmost importance. To generate a prospect’s OFP, you can’t simply average their 5 tool grades together, as a 1B should not be punished for below average speed or defense in the same manner a SS would be.

For the OFP score, use the below guide

80 – Future Hall of Famer, one of the best players in the game
70 – A perennial All Star
60 – A better than average MLB player and occasional All Star
50 – An average MLB player, likely a regular every day player
40 – An MLB backup
30 – Cup of coffee/4A type player
20 – career minor leaguer