A guide to evaluating hitting prospects

AVG/OBP/SLG

Most hitters these days are identified by their batting average, on base percentage, and slugging percentage. Averages for each are roughly .275/.330/.450. Generally, batting averages can fluctuate up to 30 points based on luck. Plate discipline tends to be an innate skill. Players either have it or they don’t, very few players dramatically increase or decrease their walk rate. Power can be learned. Most young players don’t have a lot of power. A combination of experience and maturing bodies results in growing power. Balance among the 3 stats is the key. If a prospect has a high average, but takes few walks and has little power his offensive performance is a net negative for the team. Don't be fooled just because a prospect is hitting .300! Also be wary of players with low batting averages, great OBP, and poor slugging. It means he's good at taking pitches and taking advantage of the fact that minor league pitchers are wild. However, major league pitchers have good control and if they see a hitter who can't make good contact and rarely hits the ball hard they'll ruthlessly exploit this weakness.

The defensive spectrum

The defensive spectrum was introduced by Bill James to rank the positions according to their defensive difficulty. From easiest to hardest:

1B
LF
RF
3B
CF
2B
SS
C

Correspondingly, the amount of offense required decreases down the spectrum. For instance, last year Joe Mauer hit .365/.444/.587 at catcher while Prince Fielder hit .299/.412/.602. On balance, their offensive performance was similar but because Mauer’s position is much harder to field than Fielder’s, his overall contribution was considerably more than Fielder’s.

Defensive position and aptitude are critical

Say you’re a young highly regarded SS prospect. In your first year your poor arm is exposed so the team moves you to 2B so you don’t have to make long throws. However, your mobility decreases because you’ve suddenly put on 10 kg. So the team moves you to 3B. Does this mean you are still a highly regarded prospect? Probably not. Going back to the defensive spectrum, the hitting requirements for SS are much lower than that for 3B. If you were a good hitting SS, that means you’re an above average hitting 2B and a below average hitting 3B. The only way you could maintain your top prospect status in such a situation was if you played 3B defense at an elite level. Demotions across the defensive spectrum happen all the time and is one of the most important factors in killing a prospect’s status. That’s why teams generally prefer young prospects who start as CF and SS. Not only are good ones hard to find, they still have room to fall while they learn to hit. Nobody goes from a hard defensive position to an easy one. Catchers are always risky because if their defense can’t cut it they generally are moved from one end of the defensive spectrum to 1B where their bats are generally inadequate. 1B and LF who don’t hit have nowhere to fall and can quickly be cut from the team.

Stats are important, but not that important

The minor leagues, unlike the majors are a training ground. Teams aren’t trying to win every game at all costs. Thus, players are often trying different things at the plate to strengthen their deficiencies. For example, a player is trying to develop more power by putting more loft into his swing. As a result he has a lot more popups which decreases his overall stat line. This doesn’t mean the player is declining, it just means he’s trying something new and there are going to be bumps in the road. Also, scouting reports matter more in the minors at the majors. Are you blasting home runs with a long swing in rookie ball? Your long swing will be exposed once you reach the higher levels with pitchers that know how to exploit your weaknesses.

Age

Age is the key to evaluating a prospect's performance at each level. Here's a rough breakdown of at what age top prospects reach a respective level (with a variance of one year):

low A: 21
high A: 22
AA: 23
AAA: 24

If you're a 21 year old in AAA and struggling, don't panic. You're young for the level and have plenty of time to figure things out. The fact that you're already there is a credit to your talent. However if you're blasting the ball in low A but you're 24, that's what you're supposed to do and you won't get credited for your performance. In general if a prospect is over 25 and has never reached the majors he probably has little chance of ever becoming a starter and may never see the majors.