Leveraging a Pennant: The 1928 AL

It was a two team race, with the Yankees (101-53) finishing 2.5 games ahead of the A's (98-55). Every other team was at least 10 games out from May 27 on until the end of the season. All data is from Baseball Reference and the Baseball Reference Play Index.

Even the A's were 13.5 games out on July 1 and still 12.5 out on July 17. But starting with July 16, the went 39-12 until Sept. 8 when they went up 0.5 games. Unfortunately, for them, they went just 10-8 the rest of the way, including losing 3 out of 4 to the Yankees in New York right after that.

The Yankees won the season series 16-6, outscoring the A's 138-93. The Yankees had the edge in OPS  in those games, .836-.718. In High Leverage situations, the Yankees had a huge edge, 1.108-.604.

For the entire season, the A's actually had a slightly better OPS differential .118 (.799 - .681) vs. .107 (.816 - 709). But again, if we look at leverage, shown in the tables below, we can see that the Yankees had the big edge in High Leverage situations (POPS is the OPS allowed by their pitchers).

Yankees	OPS	POPS	Diff
High Lvrge	0.877	0.704	0.173
Medium Lvrge	0.810	0.669	0.141
Low Lvrge	0.811	0.750	0.061

The year before, the 1927 Yankees, who have the highest OPS differential ever (.201), actually did not do as well in High Leverage situations as they did otherwise (I plan to do a post on that).

Now the A's. Their OPS differential in High Leverage situations was much lower than the Yankees'. Maybe this made the difference in 1928.

A's	OPS	POPS	Diff
High Lvrge	0.790	0.727	0.063
Medium Lvrge	0.758	0.647	0.111
Low Lvrge	0.817	0.693	0.124

From regressions I have done, I estimate winning pct with this formula

Pct = .5 + 1.3246*OPSDIFF

That would give the A's .656  and the Yankees .641. The A's would have 2 more wins over 154 games.

But, if we break things down by leverage, I have the following equation

Pct = .5 + .306*LOW +.420*MED + .564*HIGH

where the LOW, MED and HIGH refer to OPS differential in those cases.  That estimates the Yankees with a .670 pct and the A's with .620. That would give the Yankees 8.5 more wins over 154 games.

Now my estimates are based on more recent data and it looks like Baseball Reference might not have complete leverage data for 1928. But it does give us an idea of how the Yankees won the pennant.

Finally, here is leverage breakdown for the 22 head to head games

Head to Head OPS	Yankees	A's	Diff
High Lvrge	1.108	0.604	0.504
Medium Lvrge	0.759	0.680	0.079
Low Lvrge	0.809	0.795	0.014