The best of the week so far. That's not really saying much, but really, this had some fine clueing, and the animal simile theme is one I haven't seen before. The first themer FATASACOW (20A: Scale-busting) was almost jarringly colloquial, as was WUSS (35A: Wimpy sort), but that's a good thing! Especially after the stale and boring start to the week.
Fun clues for ERIC (11D: Holder of a cabinet position), EMBERS (8A: Ones dying in a fire?), TAILS (21D: Half of all flips), and even stalwart STA (4D: Stop on the tracks: Abbr.) is given a fresh clue. On the other hand, I didn't love LAMES (26A: Shoots in the foot, maybe), and I didn't know what OSAGE (47D: _____ orange) was (it's a tree that grows mostly in Texas). I also have never heard the expression BALDASACOOT (17D: Like a chrome-dome), but I'm assuming others have.
As I said, it's the best so far, but I'm still holding out for better things as we enter "the turn."