NL vs. AL: Which league is better?

July 9, 2008

No brainer, right?

Eric Karabell said yesterday (7/7/08 ) on his podcast that the AL was obviously the better league — I think he used the word “clobbered.”

And why not?  This year’s interleague record was 149 for the AL, to 102 for the NL.  That gives the Senior League a 0.396 winning percentage.  Friends, that’s close to Washington territory. (*)

*By the way, why did Jim Bowden think that the 2003 Reds would be any better in 2008 than they were back then? Dmitri Young, Kearns, Lopez, Aaron Boone — playing the Nationals is like Old Home Week.  Also, I’m stealing this footnote technique from Joe Posnanski.

Add to that the fact that the AL has won 8 of the last 13 World Series, and 10 straight All-Star games.  Case closed, right?

Not so fast.  When you look at the underlying numbers, it’s much less clear.

League Runs HR OBP SLG OPS
American League 409 85 0.332 0.410 0.742
National League 401 90 0.329 0.410 0.739

Gee, that looks a little closer, doesn’t it?  Those numbers are per team, to compensate for the fact that there are 16 NL teams and only 14 AL teams.

It turns out that the difference is barely statistically significant.  In runs, it’s about 1.1 standard deviations; the NL advantage in HR is about 1.5 standard deviations.  The AL numbers are better, but only slightly better — not the kind of difference you would expect would generate the lopsided interleague results.  Furthermore, we would expect the AL to be better because of the DH.  Shaving 1/9 off the AL run numbers would put them lower than the NL.

Well, lets look at the players, then.  From, the 10 best players this year in WPA are Berkman, Burrell, Holliday, Manny, Bay, Pujols, Mauer, Chipper, Uggla, and Carlos Lee.  That’s 8 NL players.  The top 10 (actually 12, because of ties) in Runs Created from

Berkman-HOU 95
Jones-ATL 88
Kinsler-TEX 86
Utley-PHI 83
Pujols-STL 80
Ramirez-FLA 79
Burrell-PHI 76
Holliday-COL 74
Sizemore-CLE 74
Bay-PIT 72
Bradley-TEX 72
Hamilton-TEX 72

That’s 8 National Leaguers of the 12.  Certainly looks like the NL can pull its weight here.

Maybe it’s the pitching?  Here’s Adjusted ERA+:

Duchscherer-OAK 194
Volquez-CIN 190
Lee-CLE 172
Lincecum-SFG 171
Danks-CHW 170
Haren-ARI 160
Sheets-MIL 156
Marcum-TOR 153
Zambrano-CHC 151
Billingsley-LAD 141

Only 6 of 10 here for the NL. But still! Around half of the best pitchers are in the NL.  And Santana, Sabathia, and Harden aren’t on that list (yet).

Jayson Stark had a chat about this topic after the first interleague weekend.  He took the position that the NL was at least closing the gap, if not even.  Of course, after that the NL really got clobbered in interleague play.

So, how can we possibly explain why the AL becomes unbeatable in interleague play?

Here’s the possibilities I’ve come up with.  Maybe you can add more.

  1. The AL pitching and hitting are both better than the NL by precisely the same amount.  Thus, they cancel each other out in AL games, but show up big time in interleague.  But then how do you explain the preponderance of NL players atop the leader boards?
  2. The NL has the stars, but the AL teams are better balanced.  The balanced teams win.  Okay, but is there a reason why we think a balanced team is better than a stars-and-scrubs team?  Also, apparently the stars and scrubs just happen to balance out to give PRECISELY the same overall stats as the even-keeled AL.  Sounds fishy.
  3. AL teams make better use of the DH, because they actually have a good hitter on the payroll to play the position.  The NL teams are using utility infielders.  Two words: Jose Vidro.  Besides, that should only matter in half the games where the AL is at home.
  4. The AL has more big-name aging stars.  The kids in the NL are simply awed, and fold.  C’mon, it’s the major leagues.  They get over it pretty fast.
  5. The leagues are actually pretty equal; it’s just been a string of bad luck for the NL.  149-102?  That’s pretty unlikely — the binomial calculation puts it at 0.15% chance if the true odds are 50/50.
  6. AL Three-True-Outcomes ball beats NL small-ball. Except that the NL has the lead in HR, BB, and K.
  7. Wait, I mean that AL small-ball beats NL Three-True-Outcomes ball.  Um, now you are reaching.

It doesn’t make any sense to me.  The NL looks roughly equal to the AL.  If I didn’t know the head to head outcomes, I’d give the NL a slight advantage.  What gives?

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4 Responses to “NL vs. AL: Which league is better?”

  1. Drew Says:

    First, let me say, I loved this post. I’ll read anyone who references TTO, Posnanski, and Fangraphs in the same entry.

    I don’t think it’s instructive at all to compare triple slash stats. The AL hitters face AL pitchers (interleague notwithstanding) so that really doesn’t prove anything. I do think that the AL pitchers and hitters are both better than their NL counterparts, which would explain the similar lines. It’s tough to really compare the true talent levels in each league without using interleague results. The interleague results, like you said, are statistically significant at the 99%+ level. What else can be used?

    1) Projections. PECOTA was more accurate last year when a factor was added to lower the talent level in the NL. The AL was projected to be better than the NL, and it was better.

    2) Payroll. The average AL payroll is over 96 million, compared to only 82 million for the NL. That’s a big difference. The AL has five of the top six payrolls in baseball. Teams may not spend their money wisely, but success does correlate with payroll.

    3) Subjective front office comparisons. There are a number of horrific franchises in the NL. The Astros, Giants, and Pirates are worse than any franchise in the AL. Aside from the Orioles, you could make the argument that there aren’t any poorly run franchises in the AL.

  2. bbjones72 Says:

    Thanks for the kind words, Drew.

    Your first argument is basically that since AL pitchers nearly always face AL batters, and likewise with the NL, that you can’t get any relative quality information.

    That’s true. However, since the overall numbers are so close, the argument is really that the AL hitters and AL pitchers are better than their NL counterparts in PRECISELY the same amounts, such that their relative performance stays the same. That seems unlikely.

    You are right that a 99% significant result in the most direct test should carry a lot of weight. I guess my question should really be not which league is better, but rather if the AL is so much better, why does it not show up in all the other stats?

    1) Projections. I didn’t know that about PECOTA. It’s a little disturbing to have to add a league-wide fudge factor, isn’t it? Essentially, that’s the same question I’m asking: why should there be a league-wide fudge factor?

    2) Payrolls. This is almost entirely a function of age. The gigantic contracts are for aging superstars — Jeter, ARod, Manny, Big Papi, Vlad, etc. The young players in the NL who are really good are often still making close to league minimum.

    3) Better front offices. This could be a good argument. But the NL teams with winning interleague records this year were the Braves, the Mets, and the Reds. Even I wouldn’t claim the Reds’ front office is brilliant. The Braves went 8-7, so they were barely over .500, and the Mets are underperforming their talent. Meanwhile, the Orioles (who will always be poorly run while Angelos owns them) were 11-7.

    All that said, we should have a great test case. The NL scored roughly 20% fewer runs than the AL. So, we should see Sabathia and Harden give up roughly 20% fewer runs in the second half. Sabathia gave up 52 runs so far — 1 S.D. on that is a little over 7, while 20% is 10.4. That should be statistically significant. Of course, we could try to use the last couple of seasons to establish a baseline with a smaller SD… Harden has only given up 20 ER so far, because he’s been hurt, as usual. That will be tougher to tell.

    Still, if Sabathia and Harden don’t dominate the NL, then it really seems there will be some ‘splainin to do, right?

  3. Drew Says:

    I find it funny that this article talks about several things we have already discussed:

  4. John Park Says:


    Whats the NL advantage when they are the home game? Nothing more than any home game. Whats the AL advantage? David Ortiz. Matsui. Bradley. Huff. Thomas. Thome. Sheffield. Hafner.

    Bigger payroll is due to having to spend on a DH.

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