Superburban, the way my mind has always interpreted that (which may very well be wrong, because I have no formal education in this stuff, just interpreting things "my way.") is kind of tough to express without being able to draw (I'm a visual type learner..), so bear with me.
60hz 3 phase, with 120* offset legs essentially gives you 180hz power, with the "peaks" occurring every 1/180th of a second, or 0.0056 second intervals. Running on "standard" power with 180* offsets gives you 120hz power at 1/120th of a second, or 0.0083 second intervals. The motor doesn't care or know that the legs are offset by the "wrong" number of degrees, they just get charged at different time intervals, given the same 60hz source power. I've always assumed this just results in a 33% reduction in RPM, all else being equal. So a 1725rpm 3ph motor will run at ~1150rpm on single phase. I think. Again, there's no formal education behind this, so I could be 100% incorrect. Just how my brain has reconciled it.
Assuming my above example to be accurate, using a rotary converter will then generate power on 120* legs, albeit at a slightly different base frequency. I'm not sure if this is true or not, as I've only ever used phase converters in *very* limited circumstances, and never a situation where I could "dig in" to see what's going on under the hood.
Static phase converters aren't really "phase converters" in any sense of the word. They do nothing to change the phase output of your power, they simply allow you to start a 3ph motor and keep it running on single phase. To my understanding, there is no "three phase" output from them at all, except an initial "jump start" to energize the third winding to get the motor running. I think "phase converter" is a bit of a misnomer for statics, but again - I'm no expert.