The 2007 infield was great at the plate but brutal afield...Braun (-32), Fielder (-15), Weeks (-10). Only by the grace of JJ (+9) did they sneak above -50 DRS by a couple runs. Put it all together and BRef says they were worth 11.0 WAR.
Robin Yount put up 10.6 WAR all by himself in 1982. Throw in another 14.5 WAR from Molly, Coop, Gumby and the 1982 infield more than doubled the 2007 infield's WAR total.
A number of those late seventies early eighties infields eclipsed 2007 pretty easily - 1977 (14.8 WAR), 1978 (16.4 WAR), 1979 (13.1 WAR), 1980 (20.1 WAR), 1983 (20.1 WAR).
For a more recent season that cleared the 2007 infield by a few wins there was 1996 with Jaha (4.2) Vina (1.7) Valentin (3.9) Cirillo (4.5) combining for 14.5 WAR.
From a total value standpoint, the 2007 infield was most comparable to years like...
1992 (11.3 WAR)
Stubbs (0.1) Fletcher (3.4) Listach (4.5) Seitzer (3.3)
1998 (11.0 WAR)
Jaha (0.0) Vina (3.1) Valentin (2.0) Cirillo (5.9)