Here Comes the National League?

One fact for you: After Tuesday, the American League has won 16 of the past 20 All-Star Games. The National League has won a lousy three, and then there was the silly one. That’s a pretty striking set of results.

Another fact for you: The fact above doesn’t really mean much. Leaving aside all the countless other considerations — we’re talking about 20 games. The Cubs have lost 14 of their past 20 games. The Phillies have won 12 of their past 20 games. The Cubs are a lot better than the Phillies. No one would ever argue that.

A third fact for you: Fans don’t really have league allegiances. It doesn’t really matter to fans which league is better. You just want your team to be good in its league, and then you want to win the last series. There aren’t rival AL and NL street gangs. Differences can exist, and so what.

But, a fourth fact: It’s often said the AL is better than the NL. It long has been. Is it still? It’s an easy thing to check up on, and we are now more than halfway through the season. We can look at things. These have been introductory facts. Let us now consider even more facts.

The greatest aid here has been the Baseball-Reference Play Index, which makes everything simple. The first natural thing to check, for this season: There have been 180 interleague contests. The AL has won 97 of those contests, for a winning percentage of 53.9%. Right there, you can say, all right, looks like the AL is still the better league. It’s a convincing point, and here’s the historical landscape ever since the dawn of interleague play in 1997.

At the beginning, there was balance, if not NL superiority. But the last time the NL won at least half the games was 2003. This would be the 13th consecutive year of AL control, and that’s a long-lasting trend. That’s precisely why people have been comfortable asserting the AL is better — there’s now an established history. This current season would fit the history.

It is possible to dig deeper, however. In one sense, wins and losses are everything. In another sense, as we all know, wins and losses can mislead, especially over smaller samples. I mean, 180 games is only a little more than a regular full season, and full-season records can be wacky. So we can look at the next level. I calculated AL runs scored per game, and NL runs scored per game. I then subtracted the latter from the former.

This plot still doesn’t change a whole lot. The last time the NL outscored the AL in interleague play was, unsurprisingly, 2003. We have the same run of 13 straight years. Of some note: The AL was most dominant between 2005 – 2009. Last year, there was a big AL spike, but that’s calmed back down. But even this year, on a per-game basis, the AL has outscored the NL by three-tenths of a run. It’s a meaningful gap.

Yet there’s one more level. Just as wins and losses can mislead, so too can runs and runs allowed. Think of it in terms of BaseRuns, if you want. Over a relatively small sample, you can have the bigger-picture numbers heavily influenced by sequencing. I know this is getting granular, and I know that teams are judged based on how often they win or lose. But, I’m intrigued by the following plot. Instead of run differential, I’ve plotted OPS differential.

In 2002, the NL had a higher OPS than the AL, by two-thousandths of a point. And then, from 2003 through 2015, the AL took the lead. Just last year, the difference was enormous, but now look all the way to the right — the NL, this year, has a tiny lead again. It’s that same margin of two-thousandths of a point. On the highest level, the AL has won more. On the next-highest level, the AL has scored more. But in terms of actual hitting and pitching — the NL has arguably been the AL’s equal. What this suggests is that the leagues are actually about balanced. Similar to how they were in 2013.

One partial explanation could be that the AL is the superior baserunning league, but I don’t see any evidence of that. I do see some evidence that AL teams have superior bullpens, on average, to NL teams, and that could influence the timing of events. I’m not convinced the AL isn’t still better. I just think, if there is an edge, it appears razor-thin.

Helping the NL out has been the collective performance of its designated hitters. As always, AL pitchers have been terrible at hitting. NL designated hitters have managed to out-hit their AL counterparts. Here’s a plot of NL DH sOPS+, and though that’s a ridiculous mouthful, this is really just showing NL DH performance relative to AL DH performance, where a mark of 100 would mean they’ve been equal.

In 2003, NL designated hitters were excellent. The same was true in 2009. It’s been true again this year. Now, in the past, those spikes have been one-offs. And this could be another one-off, but I’m just taking a snapshot of time, here, and in this snapshot, the NL has done well to find a bat on the bench. People used to complain that the NL was at a disadvantage because rosters didn’t include DH types, by design. This has been a successful season. There’s been no DH disadvantage at all.

There’s still going to be a lot more baseball. With 180 interleague games in the books, there are another 120 left to play, and the numbers could shift rather dramatically. In the AL, the first-place Orioles have played just seven interleague games. The first-place Rangers have played just eight. On the other hand, the Phillies lead the NL with 16 interleague games. And the Cubs, so far, have played just two, by far the smallest amount. I don’t know if the National League is superior to the American League. I do know it’s at least a valid question. If anybody cares, the two leagues have again found a balance.