I had no idea what was going on with the theme until I looked at it after the grid was done. I was all set to hate it, because I couldn't understand it, but then it slowly came to me and I laughed out loud, as the kids are saying these days. My favorite was SQUIRTCHASER (43A: Rug rat pursuer?) ("Skirt Chaser"). The strangest was GREATSQUAT (57A: Outstanding posture for a catcher?) ("Great Scott!"). I've seen this kind of "change the sound of one part of a word" theme before, but today it caught me by surprise, and I ended up liking it.
Our solve was done after coming home late and we were both a little sleepy, but I still think this skewed a little harder than normal. Part of the confusion was that once the answer for 15A: Area jiggled while twerking (REAR) (They went there, apparently…) was four letters and not three, I assumed it would be "Butt," and actually took out GEOM (6A: Math subj. with proofs) for a time, even though we both knew that was correct. Multi-part abbreviations also were slow to come to us, like TREX (29D: Cloned menace of film) and SQIN (55D: Newspaper ad meas.). 59D: Proterozoic ____ (EON), too, seemed strange. It's legit, but we both thought only of "era."
The fill contained what is, perhaps, my least favorite "crossword word," REUNE (47D: Attend a homecoming, say). No one says that. But on the other hand, it also contained MASON (1D: Perry who's on the case), which made Frannie quite happy.
A slightly mixed bag, but now that I understand the theme, I'm giving it a thumbs up.