1) What traits or skills do MLB teams scout for, and what do they expect players to develop over time?
2) What traits/skills do teams avoid? How do they estimate injury risk, and do they do this well? Can they?
3) What pitches generate more injuries? It seems that pitchers who throw a curveball more often get injured more (think Ben Sheets, Chris Carpenter, Stephen Strasburg). Is this really the case, and if so, is it worth the risk?
I don’t know exactly what teams look for in players beyond the five tools, tall pitchers, and possibly the “good face.” Kevin Kerrane wrote a marvelous book on scouting in the 1980s Dollar Sign on the Muscle, which follows the lives of several scouts and discusses the characteristics they look for. While there is some agreement over what makes a baseball player good, different scouts and organizations have their own philosophies as to what characteristics mark future success.
I can’t comment on how to predict success based on personal observations (a technique one of my professors referred to as “ocular least squares”), but I have looked for makers for success in minor-league performance statistics. I report my results and explain my methods for predicting success in the Chapter 8 of Hot Stove Economics. I even put a dollar value on prospects using these characteristics.
The difficulty with picking out major-leaguers before they’re ripe is that while most future big-league players excel in the minors, many bad players do as well. Looking beyond the slash stats reveals some common characteristics of big-league players, and some of the stats I found useful for predicting major-league success aren’t necessarily stats that I find to be the most useful stats for evaluating players once they make it. For example, I rarely look at the batting averages and strikeout rates of major-league hitters, but I find that high batting averages and low strikeout rates are important predictors of major-league success. You can succeed in the big leagues with a low average and striking out a lot, but even players who struggle in these areas typically handled the bat much better in the minors. Also important are a player’s walk rate and isolated power. If you have patience and can hit the ball hard, you’re more likely to succeed in the majors that players who lack these skills. And you can’t look at minor-league performances without also accounting for age. A twenty-year-old who’s treading water in Triple-A may have more promise than some of the older guys having success at the level.
Another interesting finding was that the stats below High-A ball have no predictive power. At this level, predicting success requires personal observations of trained scouts.
As for how players skills develop, I’ve done some work looking at how major-league players improve and decline over their careers. For hitters, batting average and power peak in the mid-to-late-20s, but these skills see minimal improvement and decline. The ability to walk improves into the early-30s, but the age-range of peak performance is less than it is for batting average. Pitcher strikeout ability is at its greatest almost as soon as pitchers enter the league, but this ability doesn’t diminish as fast as other skills. Like hitters, pitchers improve in walking into their early-30s. This is likely the result of acquired knowledge that allows older players to succeed, even as their physical athletic skills are deteriorating.
As for identifying injuries, that’s something that is not well-understood outside of baseball. I would hope that teams are conducting their own internal analyses of injuries, but most of that knowledge is kept private. Baseball injury data is just starting to become available where we can look at factors that influence injuries. The research being done in sports medicine journals is good and is still developing. What I have found interesting is that the medical community seems to have a better grasp on youth injuries than it does on adult injuries. For example, I’ve got a study on my desk that looks at factors that impact elbow injuries among youth pitchers—arm fatigue and mechanics seem to matter, but curve balls don’t. Play tracking systems like Pitchf/x, and motion analysis technology like Dartfish should help us better predict and prevent injuries for all players.