Here are the runs for '05 - '09 for the other divisions, plus '09 for the AL East and '05 - '07 for the NL East. I'll also include the averages for '05 - '08 (comparable to Wang's peak) and '08 - '09 (the relevant Lannan years).
AL C 05 06 07 08 09 AV-CMW AV-JL
MIN 25 13 25 4 5 17 4.5
CH-a 13 3 28 6 19 12.5 12.5
Clev 7 2 8 7 12 6 9.5
KC 21 20 27 25 23 23 24
DET 17 8 3 5 15 8 10
DIV 15 12
AL W
LAA 11 18 6 15 2 10 8.5
SEA 22 21 12 26 28 20 27
OAK 9 16 19 27 14 18 20.5
TEX 3 6 7 1 10 4 5.5
DIV 13 15
NL C
CHIC 20 28 18 2 22 17 12
CIN 4 22 14 23 24 16 23.5
PIT 28 29 23 19 30 25 24.5
HOU 24 25 24 22 27 24 24.5
St L 6 14 22 12 18 13.5 15
MIL 16 27 11 17 9 13 13
DIV 18 18
NL W
AZ 23 15 26 20 20 21 20
COL 14 11 5 18 6 12 12
LAD 26 10 21 24 11 20 17.5
SF 29 24 29 29 26 28 27.5
SD 27 26 20 30 29 26 29.5
DIV 21 19
05 06 07 08 09
Bal: 15 17 15 11 16 14.5 13.5
Bos: 1 9 4 3 3 4 3
Tam: 12 30 15 13 7 17.5 10
Tor: 8 12 17 21 8 14.5 14.5
DIV 13 10
05 06 07 08 09
ATL 10 5 9 15 17 10 16
FLA 19 19 13 14 13 16 13.5
PHI 5 4 2 9 4 5 6.5
NYM 18 7 10 8 25 11 16.5
DIV 10 13
So, in CMW's prime, the 4 non-Yankee AL East teams average offense would have been tied for 2d among all divisions, and in the Lannan era, the NL East had the 3d highest average (behind the AL East and the AL Central). It should not be a surprise that the DH environment results in more runs scores. However, you can't say that, absent the NYY, the AL East had relatively soft offense. In fact, it still had the best or near best offenses in MLB, on average.