Yeah, don't read to much into speaker 'specs'. For example, a given speaker might test to -3 db at say 30 Hz very easily at a 1 meter SPL of 70 Hz.
But, when you try to run it on up to higher SPLs, like the 100-115 dB required of a sub at Dolby reference levels, it might drop WAY down at those frequencies.

In other words, just like most other 'measurements' or statistics, speaker frequency responses are easily manipulated, and misunderstood even easier.