Background
The authors write that "the accurate representation of precipitation is a recurring issue in climate models," and they note, in this regard, that "El Nino-Southern Oscillation (ENSO) precipitation teleconnections provide a test bed for comparison of modeled to observed precipitation."

What was done
Langenbrunner and Neelin assessed the simulation quality of the atmospheric component of models in the Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) by comparing the ensemble of runs driven by observed sea surface temperatures (SSTs) to observations made during 1979-2005 and to the ensemble results of CMIP phase 3 (CMIP3).

What was learned
The two U.S. researchers report that "the ability of the model ensemble to yield amplitude and sign measures that agree with the observed signal for ENSO precipitation teleconnections lends supporting evidence for the use of corresponding measures in global warming projections." However, they acknowledge that (1) "within regions of strong observed teleconnections (equatorial South America, the western Equatorial Pacific, and a southern section of North America), there is little improvement in the CMIP5 ensemble relative to CMIP3 in amplitude and spatial correlation metrics of precipitation," that (2) "spatial patterns within each region exhibit substantial departures from observations, with spatial correlation coefficients typically less than 0.5," and that (3) the amplitude of the multi-model ensemble mean "is systematically smaller (by about 30%-40%) in the selected teleconnection regions."

What it means
But what the heck. The results are apparently good enough for government work. Or must we now say university work???