Explain the differences in AL and NL rules to a casual baseball fan

I live in DC and grew up in the area. The Senators left town when I was a toddler, so I never really paid much attention to the game until the Nats came to town. I’m a casual fan, I go to a few games a year and I read about each game after it is played.

I know the AL and the NL have slightly different rules. Can someone break them down for me? Also, so this is interesting to real baseball fans, what are the advantages and disadvantages of these rules?

Extra credit question: In today’s Washington Post article, Gio Gonzalez said "“It was terrible,” I turned to the dugout and the first thing I said was, ‘I’m going back to the American League, so I don’t have to slide anymore.’ That’s never going to happen again.” Why don’t they slide in the AL?

The biggest difference is that in the National League, pitchers have to bat, as is right and just. The American League uses the blasphemy otherwise known as the Designated Hitter–a guy that bats in place of the pitcher.

Gonzalez is a pitcher, so if he goes back to the American League, he would not be batting, and thus could avoid the need to slide while running the bases.

This rule also affects managers in the National League. They tend to susbtitute a bench player to hit for the pitcher when they intend to remove the pitcher from the game. This effectively uses up the bench player—who will then be replaced by another pitcher in the next inning, and is no longer eligible for that game. Choosing to pull a pitcher is thus a more subtle strategic decision in the National League.

In the American League, they can change pitchers without the need to use up a bench player, as their hitting lineup will not change in that situation.

Oakminster nailed it in 1.

Thanks, so does this affect the playing style of NL and AL teams?

Because the pitcher hits 2-4 times a game (among other reasons), in general offense is lower in the National League. When offense is lower, teams tend to play “small ball” a lot more, which involves stealing bases, bunting, hit-and-runs, and the like. American League baseball is a bit more station-to-station, trying to get the big hit.

These are generalities of course, there are NL teams that don’t run and AL teams that do, but it bears true as a general trend.

Other than the DH, I can’t think of any specific rules that are different between the two leagues. A lot of practices that were different have been smoothed over. It used to be that NL home plate umpires used external chest protectors while AL umpires used internal padding when they had home plate duty. This gave the two leagues slightly different strike zones. Now everyone used the same and the umpires are not assigned by leagues. Back in the 1960s-80s when lots of home parks had artificial turf (the foulest abomination known to man since alcohol-free beer), for some reason many of the NL parks had it while only a few AL teams did. Players run faster on phony turf and the balls go quicker on it so there was a premium on stealing base runners, fast outfielders to prevent balls getting to the outfield and infielders with stronger arms because they had to play deeper. Plus for some reason the NL of the 1960s and 1970s had more Black and Latin players than the AL did and for whatever reason there are more Blacks who run faster than Whites. But phony turf has disappeared and I think there isn’t much difference in the racial balance between the two leagues.

Not only do in-game strategies differ from AL to NL, but even the construction of the roster can be different. NL teams, prone to small ball, might value speed over power. The opposite would be true for AL teams.

Another possible difference that I won’t bother doing too much research on at the moment is that NL parks seem to be typically smaller than AL parks in terms of playing field dimensions. There are outliers, like San Diego, which is huge, but in general, the newer NL parks have been relatively small. Pittsburgh, Cincinnati, Houston, San Francisco, to name a few. Meanwhile, Seattle, Chicago White Sox and Detroit, for example, have large parks. My perception might be way off and I welcome anyone to refute me with facts because, again, I haven’t done the actual research.

Park size (at least how the park plays, not necessarily the actual physical dimensions) seem to be pretty even between the two leagues:


That’s just a one year sample, but as you can see, it goes AL-NL-NL-AL-AL-AL-NL at the top, and NL-AL-NL-NL-AL-AL at the bottom.

The only new park this year is Marlins Park, which so far is higher than average in runs scored but lower than average in home runs. The usual caveats about SSS apply.

In 2011, AL teams stole more bases per team than NL teams. Also in 2010. And 2009.

Generally speaking there isn’t any significant way AL and NL teams play except in terms of what the manager does when the pitcher comes up, which is usually to bunt (early in the game) or pinch hit (if later.) So sacrifice bunts are much higher in the NL, but that’s almost entirely because of pitchers bunting. And actually, that’s much less of a difference than you might expect, about one successful sacrifice bunt every four games.

There might have been a difference many years ago, but in modern times strategy has more or less coalesced around an ideal set of low-risk approaches.

That could just mean that the NL has catchers with better arms.

Or more pitchers using the slidestep.

How about 2008? Or 2007? or 2006? Or 2005, 2004, 2003, or 2002? I think you know the answer to these: It’s the NL.

Obviously there can be fluctuations in personnel between the leagues (better/worse catchers and baserunners) that will enable the AL to have more stolen bases, but as a general trend the NL steals more. Since the DH was instituted in 1973, the NL has beaten the AL in yearly tally by the score of 28-11.