Why are the Red Sox better today? Sabremetrics or Construction?

I saw an article this morning from an MIT professor that predicted the Red Sox would win 100 games this year. That is a pretty bold statement since the Red Sox have only won 100 games in a season three times (1912, 1915 and 1946). However, it got me to wondering how have the Red Sox become so good in recent history. I often heard comments the claim that it is the payroll or the genius of Theo Epstein. Whenever I am with statistics guys, it is the hiring of Bill James and the use of Sabremetrics that made the difference. I have a third theory to put forth as the major reason for the improvement of the Red Sox in recent history, construction at Fenway. Oddly, this started the same year that Bill James was hired by the Red Sox, 2003.

From 1995 to 2002 the Red Sox had a combined record of 695-582 winning 54.42% of their games. From 2003 to 2010 the Red Sox had a combined record of 749-547 winning 57.79% of their games.

Year	W	L	Winning %		Year	W	L	Winning %
2010	89	73	54.94%		2002	93	69	57.41%
2009	95	67	58.64%		2001	82	79	50.93%
2008	95	67	58.64%		2000	85	77	52.47%
2007	96	66	59.26%		1999	94	68	58.02%
2006	86	76	53.09%		1998	92	70	56.79%
2005	95	67	58.64%		1997	78	84	48.15%
2004	98	64	60.49%		1996	85	77	52.47%
2003	95	67	58.64%		1995	86	58	59.72%
	749	547	57.79%			695	582	54.42%

So they are a got better after 2003 and Theo is a genius and Sabremetrics rules baseball. I am not so sure, and I think we reach those numbers based on a Simpson's paradox. Let me explain. If Sabremetrics had been the driving reason for the improvement the Red Sox. they would have gotten better not only at home but away as well. They did not. In fact the Red Sox improved massively at home, but got worse on the road. So what is the factor that explains this? In 2003, the same year Bill James was hired by the Red Sox, additional seating was added the Fenway park for the first time since it was 1946. While it was was always known that Fenway was helpful to certain types of hitters and pitchers and the Red Sox teams have always emphasized those players. I believe that construction made the park even more baised than it was before.



During the period 1995 to 2002 the Red Sox had a better away record than they did from 2003-2010.

Away Record W L % W L % 2010 40 41 49.38% 2002 51 30 62.96% 2009 39 42 48.15% 2001 41 39 51.25% 2008 39 42 48.15% 2000 43 38 53.09% 2007 40 41 49.38% 1999 45 36 55.56% 2006 35 46 43.21% 1998 41 40 50.62% 2005 41 40 50.62% 1997 39 42 48.15% 2004 43 38 53.09% 1996 38 43 46.91% 2003 42 39 51.85% 1995 43 28 60.56% total 319 329 49.23% 341 296 53.53%

For Home games it is a very Different story: Home Record W L % W L % 2010 49 32 60.49% 2002 42 39 51.85% 2009 56 25 69.14% 2001 41 40 50.62% 2008 56 25 69.14% 2000 42 39 51.85% 2007 56 25 69.14% 1999 49 32 60.49% 2006 51 30 62.96% 1998 51 30 62.96% 2005 54 27 66.67% 1997 39 42 48.15% 2004 55 26 67.90% 1996 47 34 58.02% 2003 53 28 65.43% 1995 43 30 58.90% total 430 218 66.36% 354 286 55.31%

MIT economist says Red Sox will win 100 games in 2011