Editor's note: This is an excerpt from Bill James' new book, "The New Bill James Historical Baseball Abstract." Check back Thursday for three of Bill's player comments: Barry Bonds, Rickey Henderson and Joe Morgan; and two more on Friday: Henry Aaron and Christy Mathewson.

The 1990s: How the Game Was Played

The outstanding features of baseball in the 1990s were record numbers of strikeouts, home runs, relief pitchers, and new stadiums. The game was essentially defined by batters using bats with very thin handles, and whipping them through the strike zone as fast as possible, producing either extra base hits or strikeouts.

In 1967 there were 11.98 strikeouts for each major league game (5.99 per team). Several things were done to change that. Strikeouts drifted downward until 1981, when there were slightly less than 9.5 strikeouts per game. Since then there has been a resumption of the historical trend toward more strikeouts, which dates to the 1920s. Strikeout rates passed the 1967 high-water mark in 1994 and pushed on to levels about 10 percent higher by decade's end.

But whereas the strikeouts of the 1960s were caused by the dominance of power pitchers, the strikeouts of the 1990s were caused more by the predominance of power hitters. Babe Ruth, in his time, regularly led the league in strikeouts; so did Jimmie Foxx, Mickey Mantle, Reggie Jackson, Mike Schmidt, and many other power hitters. Mark McGwire, Ken Griffey Jr., and Albert Belle don't strike out any more than Mantle, Jackson, or Schmidt, but there are simply more players now who are swinging for the fences -- and thus, more strikeouts.

So the 1990s presented the paradox of historically high strikeout rates, simultaneous with historically high batting averages. Major league batting averages have hovered between .265 and .270 since 1994, the highest they have been in fifty years.

The question of why home-run hitting exploded in the 1990s is much debated. There are two popular theories that I will comment on in passing:

1. That the ball is livelier.
2. That there is a shortage of good pitching.

I put little stock in either of these explanations. The resiliency of baseballs is tested regularly, has been for many years; it's probably up some. It might be better if the resiliency of the balls was reduced, but it hasn't increased dramatically.

In all sports, whenever one person succeeds another must fail. When the hitters rule the game, this can always be explained as poor pitching, and vice versa. In addition, there is always a perceived shortage of good pitching, because each team needs a dozen or more pitchers. If a team has a shortstop they're not looking around for another, so they're not going to complain about the shortage of good shortstops. But even if a team has eight good pitchers they still need more, so some people are always going to complain about the lack of good pitching. I don't put any stock in this as an explanation for why baseball in the 1990s is the way it is.

Expansion? Expansion favors neither the hitter nor the pitcher, on balance; it does as much to create a shortage of good hitters as it does to create a shortage of good pitchers.

In the early 1990s the strike zone was a real problem, or the umpires if you prefer. From the mid-1980s into the early 1990s many umpires just would not call a strike, particularly strike three, no matter how perfect the pitch. That was maddening, and people still complain about it, but it is really not true anymore; the leagues have addressed the issue, and almost all of the umpires now will call a strike a strike. It hasn't made much difference.

In my opinion, the hitting conditions of the 1990s are created by six factors: the new ballparks, which have tended to be hitter's ballparks, and the culmination of five historical trends, which are:

1. The acceptance of strength training.
2. The abbreviating of pitcher's motions.
3. The use of aluminum bats in amateur ball.
4. The policy of fining and suspending players automatically when there is a fight.
5. The evolution of bat design.

The battle for the acceptance of strength training in baseball took at least seventy years to run its course. Honus Wagner believed in strength training, and used dumbbells as a part of his off-season workouts -- but there was, at that time, an entrenched prejudice against weight-lifting by baseball players (and most other athletes). Strength training, it was believed, would make players muscle-bound and result in injuries. In the early 1980s, when Lance Parrish reported to spring training one year sporting ten pounds of extra muscle, Sparky Anderson complained that Parrish needed to decide whether he wanted to be a catcher or a member of the Russian Olympic weight-lifting team. There are still people today who believe this, but they are now badly outvoted.

A second factor is pitcher's motions. Rent a tape of a World Series from the 1950s, even the early 1960s, and you will be struck by the pitchers' mechanics. Pitchers in that era used very high leg kicks, some of them, and pumped their arms vigorously up and down in the process of delivering the pitch. They vaulted forward in completing the pitch, although they would shorten the delivery somewhat with runners on base.

But that was problematic, because many pitchers lost effectiveness with runners on base, and even the shortened "stretch" motions were, in retrospect, not all that short. From the time of Maury Wills (1962) until the mid-1980s, pitching coaches constantly encouraged young pitchers to shorten their deliveries. The pitching motions that are common today are totally different from those of the 1920-1965 era -- and it is very likely that, as a consequence of this, the pitchers don't throw as hard. I don't want to generalize, but there may not be as many pitchers now who throw 90-plus miles per hour as there were in the 1950s, primarily because the pitchers use such conservative motions that they don't get much out of their legs.

Third, the aluminum bats. In the 1980s, when the college programs switched to aluminum bats, it was commonly said that this was going to ruin the hitters. With the aluminum bat, even if you don't hit the ball well, it will still carry. If you get jammed with an aluminum bat but happen to meet the ball squarely, you've got a base hit, whereas if the same thing happens with a wooden bat you've got a bat handle. If you swing late at an outside pitch with an aluminum bat, you can drive the ball hard to the opposite field.

In the 1980s, it was widely believed that the use of aluminum bats would ruin young hitters, and might cause another pitcher's era. This proves again that it is impossible to anticipate history. The effect that this has had on major league baseball is exactly the opposite of what was expected.

It has always been considered a sucker's game for a hitter to try to drive an outside pitch. Up until 1990, young hitters were always taught either to lay off the outside pitch or to go with it and guide it into the opposite field. If you try to "drive" that ball, they were told, you're going to wind up with a ground ball to second base (if you're right-handed) or shortstop (if you're a lefty). The aluminum bats were supposed to ruin hitters because they were going to let young hitters get by with this destructive habit of trying to drive the outside pitch.

But in fact, what the hitters learned from using the aluminum bats was not that they couldn't hit the outside pitch hard, but that they could. The aluminum bat revolution is, in a way, very similar to the Babe Ruth revolution. Before Babe Ruth, hitters had been taught for fifty years that it was a sucker's game to try to hit long flies. Up until 1920, any young hitter who experimented with an uppercut was told to cut it out and swing level, because everybody "knew" that if you uppercut you would hit a few home runs, but you'd hit twenty times as many fly outs and pop ups. Babe Ruth was "allowed" to uppercut, and wasn't coached out of it, because

1. he was a pitcher, and
2. it wasn't Ruth's nature to do what he was told.

Well, what's happened here is really the same thing: everybody "knew" that you couldn't make a living by crowding the plate and driving the outside pitch to the fence, but it turned out that everybody was wrong. We first noticed this, some STATS guys and I, after a comment that Greg Maddux made. Maddux said that the biggest change in baseball since he came into the league was in the number of hitters who stand right on top of the plate and hit the outside pitch. He said that when he came in the league (1986) he saw maybe a half-dozen opposite-field home runs all season. Now you see them all the time.

We checked that out, since we have mountains of data including things like where home runs are hit, and we found it to be absolutely true. The number of opposite-field home runs has, in fact, nearly tripled since 1987. Meanwhile, the number of hit batsmen has more than doubled, from 32 per 100 games in 1984 (31 in 1980) to 65 per 100 games in 1999. The batters have learned that they can stand right on top of the plate and blast away at the outside pitch.

The people who have picked up bad habits from the aluminum bats haven't been the hitters, but the pitchers. Young pitchers used to be taught to work inside, to jam the hitters. You can't teach that in amateur ball now, because it doesn't work with aluminum bats.

This trend was given a booster rocket in the early 1990s, when the leagues developed policies of automatically expelling players who charge the mound after a brushback, automatically suspending players who leave the dugout during a fight, and automatically expelling a pitcher who throws close to a hitter after a warning.

This, again, is a battle that goes back many, many years; I can show you baseball guides from the twenties, thirties and fifties talking about how fights develop after inside pitches and suggesting what ought to be done to prevent this from happening. The effective policy of the 1990s -- and it has been a very effective policy, in terms of limiting fights -- is no tolerance for brushback pitches, no tolerance for charging the mound.

In addition, hitters now use batting helmets with ear flaps, which reduce the batter's fear of an inside pitch, at least a bit. For all intents and purposes, the league policy now is that the hitter can stand right on top of home plate, and the pitcher can't do much about it. A few pitchers can still get by with knocking the hitter back off the plate, but not very many; that's pretty much a lost art. The batters own the inside corner.

Finally, there is a hundred-year trend in bat design. Nineteenth-century bats had barrels almost as thick as the hitting area. Bats from 1920 had thinner handles, from 1950, still thinner, from 1980, still thinner, from 1999, thinner yet. More and more of the bat's weight has been concentrated into the sweet spot, the contact area; even the end of the bat has been hollowed out to increase a little bit more the ratio between the bat's weight and its surface area.

The effect of this is to increase bat speed. The hitters of the Nellie Fox/Richie Ashburn type, who choked up on the bat and tried to punch the ball into the outfield, are just about gone. Almost everybody now holds the bat right down on the knob, and tries to hit the ball hard.

Batters used to "bone" their bats, rubbing them hard with a bone or something similar to compact the surface wood just a little, making the bat harder. In the mid-1990s batters learned that they could accomplish the same thing by "double dipping" the bat, putting an extra layer of lacquer on the bat. This also has contributed to the home run explosion.

Finally, the new parks, and in particular the addition of Coors Field to the mix, have contributed somewhat to the increases in home runs and scoring. Although this factor is not as large as I once believed it to be, Coors Field is the best hitter's park in the history of baseball (excepting temporary and transitional stadiums), and colors the statistics of the entire league. Even apart from Coors, the new parks of the last ten years have tended to improve playing conditions for hitters, as opposed to pitchers.

So putting those things together, we have the baseball of the 1990s -- lots of doubles, lots of homers, lots of strikeouts. Sit-on-your-ass baseball, as Whitey Herzog has termed it. Triples have declined from 56 per 100 games in 1977 to 32 per 100 games in 2000, primarily due to the gradual disappearance of artificial turf. Intentional walks have declined from 69 per 100 games in 1989 to 40 in 2000, because everyone is a power hitter now, so it is no longer possible to pitch around the power hitters. Stolen base rates have been declining since 1983, although they remain high by historical standards. Errors are down, double plays up -- again, consistent with long-term historical trends.

There is, finally, the revolting development of constant pitching changes. Again, this is the culmination of a hundred-year trend. Teams in 1876 used one pitcher. In 1890 they used three or four, in 1920, using 25-man rosters, seven or eight. When I was young (in the 1960s) teams carried eight or nine pitchers; in the 1970s, nine or ten; in the 1980s, ten to twelve, and in the 1990s, eleven to thirteen.

Well, if you have that many pitchers, or that many people who pretend to be pitchers, of course you have to get them into the game. Thus it is that the latter innings of modern baseball games are constantly delayed by pitching changes which have one-half the entertainment value of a good screen saver, and which incidentally deliver their managers an advantage too small to be detected with the naked microscope. The number of pitchers used per game has been increasing for a hundred years -- but increased more rapidly between 1983 and 1995 than ever before. In 1983 major league managers used 1.60 relievers per game; in 1995 they used 2.45, a 53% increase in 12 years. Projecting that rate of increase for another two generations, by the year 2020 major league managers would be using six relievers per game.

Some of you may believe that every year in the 1990s we saw new and higher levels of home runs and runs scored. This is untrue; in fact, we reached a plateau in 1994. There has been little change since then.