Evaluating Team Defense

I just want to take a moment to point out yet another soccer blog, this one focused on the Colorado Rapids. It's View From The Couch. One bone I have to pick is with the idea that the Rapids had the 3rd best defense. I didn't walk away from 2007 thinking Colorado had the 3rd best defense in the league. I didn't think GA in itself was a good indicator. I think one needs to look at shots allowed and shots on goal allowed. When you look at that, you can see why I walked away with that gut feeling. Colorado more or less allowed other teams to take just as many shots as many other teams in the league. The key is that they only Houston allowed less shots on goal. Now SOG is not an exact measurement of the number of quality scoring chances given. I would argue that allowing the shot in the first place indicates some level of chance. But the Rapids allowed only 320 SOG by opposing teams. Other than Chivas USA, that is a lot better than most teams in the league. Bouna Condoul was a big part of that but the defense at a whole helped, too.

What other things can we see from these numbers? I think they show DC United relied on Troy Perkins to save their butts more than their GA indicates. It also shows that Real Salt Lake by far had the worst defense in the league.
Note: SOG (below) really is Shots On Goal Allowed. My apologies for any confusion.

By GA
Team	GA	Shots	Shots / 90	SOG	SOG / 90	Saves	Saves / 90	Saves / SOG	GA / 90	GA / SOG
Houston	23	280	3.111	118	1.311	93	1.033	0.788	0.256	0.195
Chivas USA	28	324	3.600	125	1.389	100	1.111	0.800	0.311	0.224
Colorado	34	320	3.556	161	1.789	121	1.344	0.752	0.378	0.211
DC United	34	349	3.878	164	1.822	124	1.378	0.756	0.378	0.207
Chicago	36	351	3.900	157	1.744	123	1.367	0.783	0.400	0.229
New England	43	359	3.989	169	1.878	120	1.333	0.710	0.478	0.254
Columbus	44	354	3.933	152	1.689	131	1.456	0.862	0.489	0.289
FC Dallas	44	381	4.233	158	1.756	112	1.244	0.709	0.489	0.278
Kansas City	45	342	3.800	159	1.767	110	1.222	0.692	0.500	0.283
NYRB	45	366	4.067	168	1.867	116	1.289	0.690	0.500	0.268
RSL	45	403	4.478	205	2.278	152	1.689	0.741	0.500	0.220
Los Angeles	48	388	4.311	179	1.989	125	1.389	0.698	0.533	0.268
Toronto FC	49	352	3.911	169	1.878	115	1.278	0.680	0.544	0.290
By SOG
Team	SOG	SOG / 90	Shots	Shots / 90	Saves	Saves / 90	Saves / SOG	GA	GA / 90	GA / SOG
Houston	118	1.311	280	3.111	93	1.033	0.788	23	0.256	0.195
Chivas USA	125	1.389	324	3.600	100	1.111	0.800	28	0.311	0.224
Columbus	152	1.689	354	3.933	131	1.456	0.862	44	0.489	0.289
Chicago	157	1.744	351	3.900	123	1.367	0.783	36	0.400	0.229
FC Dallas	158	1.756	381	4.233	112	1.244	0.709	44	0.489	0.278
Kansas City	159	1.767	342	3.800	110	1.222	0.692	45	0.500	0.283
Colorado	161	1.789	320	3.556	121	1.344	0.752	34	0.378	0.211
DC United	164	1.822	349	3.878	124	1.378	0.756	34	0.378	0.207
NYRB	168	1.867	366	4.067	116	1.289	0.690	45	0.500	0.268
New England	169	1.878	359	3.989	120	1.333	0.710	43	0.478	0.254
Toronto FC	169	1.878	352	3.911	115	1.278	0.680	49	0.544	0.290
Los Angeles	179	1.989	388	4.311	125	1.389	0.698	48	0.533	0.268
RSL	205	2.278	403	4.478	152	1.689	0.741	45	0.500	0.220
By Shots Allowed
Team	SOG	SOG / 90	Shots	Shots/ 90	Saves	Saves / 90	Saves / SOG	GA	GA / 90	GA / SOG
Houston	280	3.111	118	1.311	93	1.033	0.788	23	0.256	0.195
Colorado	320	3.556	161	1.789	121	1.344	0.752	34	0.378	0.211
Chivas USA	324	3.600	125	1.389	100	1.111	0.800	28	0.311	0.224
Kansas City	342	3.800	159	1.767	110	1.222	0.692	45	0.500	0.283
DC United	349	3.878	164	1.822	124	1.378	0.756	34	0.378	0.207
Chicago	351	3.900	157	1.744	123	1.367	0.783	36	0.400	0.229
Toronto FC	352	3.911	169	1.878	115	1.278	0.680	49	0.544	0.290
Columbus	354	3.933	152	1.689	131	1.456	0.862	44	0.489	0.289
New England	359	3.989	169	1.878	120	1.333	0.710	43	0.478	0.254
NYRB	366	4.067	168	1.867	116	1.289	0.690	45	0.500	0.268
FC Dallas	381	4.233	158	1.756	112	1.244	0.709	44	0.489	0.278
Los Angeles	388	4.311	179	1.989	125	1.389	0.698	48	0.533	0.268
RSL	403	4.478	205	2.278	152	1.689	0.741	45	0.500	0.220