Minor League Baseball Isn't the Same Game

Twenty years ago Bill James made the somewhat startling claim that minor league results, "properly evaluated", predicted major league results as well as major league results do. He then made some statistical calculations called "major league equivalents" that purported to translate a player's minor league results into equivalent major league results.

Looking at James original calculations, there are people who were never successful in the major leagues who had outstanding "minor league equivalent" seasons. There are now several different systems out there to "properly evaluate" minor league players using statistics by creating their major league equivalents. It is difficult to completely evaluate these system sbecause most of them are moving targets that get "refined" each year. (A problem that is ubiquitous in the sabr community.) Perhaps as important, it is not clear what the criteria are for success. Most of the recent systems don't even attempt to evaluate players below AA and James himself made no claims about pitching results.

The problem is that sometimes major league success predicts future major league success. And sometimes it doesn't. The same is true of minor league success. In fact, when "major league equivalences" are criticized for their failure to accurately predict major league success, the usual defense is to point to similar failures in major league statistics. There is no doubt that statistics are crude tools for player evaluation, but for identifying prospects they are even cruder. There are many career minor league players who have had success while only getting, at most, a sip of the big leagues.

So why is minor league success not an accurate predictor of major league success? The answer is really that minor league baseball is not the same game. This is not to suggest the rules are different. Or that the skills that make a successful major league player won't make that player successful in the minor leagues. But some of the flaws that exist in every minor league player, the things that keep them in the minor leagues, allow other players to be successful even with their own flaws that keep them in the minor leagues.

We have all heard about the young hitting prospect who fails because they never learn to hit a breaking ball. In the minor leagues, there are a lot of pitchers who can't get their breaking pitches over the plate. Which means the hitter can have success by laying off the breaking ball and only swinging at fastballs. Most major league pitchers will just feed them a steady diet of breaking balls in the strike zone unless they show they can hit them.

Likewise, there are minor league players who have to "cheat" on 90+ fastball. Fortunately, they can cheat in many situations since they know a fastball is coming. Its the only pitch the pitcher can throw consistently for a strike. And the pitchers who can control their other pitches often lack 90+ fastballs. If they had stuff and control, they would already be in the major leagues. The flip side of that, for the pitcher, is that with a 95+ fastball, you don't need to throw anything else because, even cheating, that hitter is going to have a tough time catching up to it.

So what are some of the other differences?

In the minor leagues hitters will chase breaking pitches out of the strike zone, while major league hitters will lay off it and force the pitcher to throw strikes.

In the minor leagues, a pitcher can have success throwing hard and harder. In the major leagues, they need to be able to change speeds because no matter how hard they throw the hitters can catch up with it if they know a fastball is coming.

In the minor leagues, you can be a successful hitter with large holes in your swing because many pitchers lack the control within the strike zone to consistently take advantage of those holes. Major league pitchers largely don't.

In the minor leagues, you can have success sitting on fastballs. In the major leagues, you have to be able to hit a pitcher's breaking ball.

In the minor leagues, a pitcher needs to be able to throw the ball over the plate. In the big leagues, the pitcher needs to be able to throw quality strikes and locate their pitches in the strike zone.

Of course major league players have flaws too. Which brings us to the most important difference. There is a huge jump from the minors to the majors. People tend to think of baseball talent as a pyramid with the only a few players at the peak. But the reality is that it is more like a mountain, with the slope becoming steeper and steeper the higher you go. The difference between AAA players is not remotely comparable to the difference between big league players.

Just consider the difference between a major league star who gets 33 hits in 100 at bats and the marginal major league player who gets 25. A comparable difference for the next level would be a hitter only able to get 17 hits, well below the Mendoza line. While the jump from the minors to the majors is large, its not that large.

Does that make minor league results meaningless? No. But it means that without understanding the context of those results you can get fooled into thinking a minor league player is better than he is.

How about worse? Are there players who struggle in the minor leagues and then blossom at the major league level? Not really very often. Where they do, the issue is usually less their skills than that the minor leagues focus on player development. Players are sometimes asked to do things that reduce their immediate success in order to develop the skills they need to be successful in the big leagues. Pitchers, in particular, may be working on pitches that they wouldn't be throwing if success were the only criteria. They are working on a changeup or locating their breaking pitchers. And managers will leave a pitcher in the game even when they might be struggling. Likewise hitters, especially as they move to a new level, may be asked to shorten their swing or change their approach in other ways that reduce their immediate success.

The key thing to remember is that it is a different game when most pitchers throw 90+ and most hitters can hit a 90+ fastball. Its a different game when most pitchers can throw breaking balls for strikes and most hitters can hit a breaking ball. Its a different game when most pitchers can locate a pitch in the strike zone and hitters don't easily chase pitches that are out of the strike zone. Major league baseball is a different game than minor league baseball. And while minor league success is not meaningless, its not always meaningful either.

Measuring Defense

How important is defense? Anyone who follows the Twins found out over the weekend as the Twins defense implouded with Jose Offerman playing second base and the newly recalled Justin Morneau at first. The White Sox scored at least four runs they shouldn't have and that is being charitable to the Twins. With the exception of a few roto-rooters, most everyone agrees that defense is an important part of the game. The problem is measuring the contributions of individual players.

There are really two parts to this question. The first is the relative role of the pitcher and the fielders. The second is how we measure the fielders. Statheads are fond of the idea that pitchers have no control over how often a ball in play goes for a hit. According to this theory, it is entirely dependent on the fielders (or almost entirely, depending on the level of fanaticism of the proponent). Logically this has lead some people to measure team defense in terms of the team's batting average on balls in play. One Twins blogger over the weekend suggested this when looking at the batting average on balls in play of Twins pitchers this year. According to this theory, the 35 runs Twins pitchers gave up in their three losses could be attributed to poor fielding. At least every run not attributable to a walk or home run.

That theory seems to ignore the observation that those fielders were trying to catch some pretty hard hit balls. And If pitchers don't effect how hard a ball is hit - how are they responsible for home runs. This theory seems like the kind of wild-eyed nonsense that comes from staring at spreadsheets instead of watching baseball games. The fact is that pitchers do have an impact and the statistical data, not filtered through a preconceived ideological position, supports that. There is a reason Randy Johnson recently became the oldest pitcher to pitch a no-hitter, and it wasn't the Arizona Diamondback's defense.

So while defense plays a role in preventing hits - a role roto-players used to dismiss as unimportant - pitching is also an important component. This contributes to the difficulty of measuring the play of individual fielders. More on that tommorrow.

Hot Starts Can Fool You

Justin Morneau, one of baseball's hottest prospects, finally got called up to the major leagues by the Twins this week. The stats crowd has been talking about Morneau since last year. They are convinced that those minor league numbers can be translated directly to major league performance. Last year when Morneau was called up, he rewarded them with a hot start including a home run in his first game. Unfortunately he faded quickly and ended up back at AAA. Some unconvinced statheads attributed this either to the Twins failing to be patient enough with him or to a lack of playing time.

This year, Morneau again started extremely hot in the International League. He was hitting well over .400 with 8 home runs going into May. The demands from the stats crowd for him to be called up became a chorus. In fact, ESPN's Rob Neyer just this week talked about how much better the Twins would be if they called him up.

Well they did. And he got zero hits while making defensive miscues that contributed to at least four extra runs by the White Sox in his first game. We will see how he does from here - one game is hardly a test. But if one looks at Morneau's performance after that hot start there is some reason for scepticism. Until he was called up, Morneau had hit about .250 for May with an even sharper drop in his slugging percentage. His hot start kept his average in the mid-300's but there is little reason to think that is any more accurate a measure of his overall ability than the mid-400's average of April. Its possible Morneua's International League numbers are just a reflection of a red-hot start, rather than a player who over-matched his competition.

And that is the problem with hot starts, their effects can linger for a long time. The same thing happened with Bobby Kielty last year. When the Twins traded him for Shannon Stewart people looked at his overall numbers and thought they were giving up a budding star. One Twins blogger even predicted Kielty would produce more than Stewart over the remainder of the year. But in truth, Kielty's numbers were based almost entirely on his hot start in April. After that, he was hitting near the Mendoza line (an average of .200). While he still drew walks, they didn't really add that much to his overall offensive value.

Kielty actually had decent stats the previous year as well. But even then, his full-season results were heavily weighted with a hot start. If one looked at his month-to-month performance, Kielty's production since he was traded last year have been far more in line with what should have been expected than his season averages when he was traded.

The Twins are seeing the same effect with Lew Ford - who started hot and has cooled off. His overall stats are still pretty good, but they are really a reflection of that hot start. At the end of the year that hot start will still be making him look better than he really is. If he continues to hit the rest of the year the way he has recently he will be a decent fourth outfielder. But no one will consider him replacing Torii Hunter as some over-enthusiastic Twins fans did during his hot start.

The flip side of the hot start is players who start out stone cold - like Derek Jeter has this year. His overall numbers may end up the same as last year but he probably won't fully make up for that cold start until September. That cold start will cast a pall over this season's averages for a long time, just as Kielty's hot start inflated his worth last year. Bobby Crosby, the heralded Oakland shortstop prospect, would be an example of a young player who started out cold hitting only .200 in April. His average now is only up to .265 and it may take him a long time to catch up with Lew Ford and he may never do that this year. That doesn't mean he is not already as good an offensive player as Ford.

In-season comparisions of players stats are interesting - but they are rarely very useful in really comparing players' current value. Sometimes that is true even over a couple of seasons. Those hot (and cold) starts can fool you.