With those disconnected, the PCM defaults to a base/safe tune so the engine can still run. This is a common test for someone suspecting a faulty MAF or MAP. If you make the PCM ignore the alleged faulty sensor's input by unplugging it and the engine runs better on the PCM's default tuning, chances are the sensor is reporting erroneous info to the PCM.
It's not "pulling the data out of it's ass". It's referring to the tables it has developed for when those sensors were reporting. Throttle angle was part of those tables so now it's making a guess of the engine load based on that. It now can only rely on throttle angle, knock sensors and O2 sensors to calculate the required fuel at a given RPM. It starts out a little rich to be safe.