It looks like it also fell into the curse of the "whoops, we underestimated our player base and made things too easy in the first week" game, so they patched it to tweak with things.
The problem seems to be that they boosted all the creatures in the wild, but none of the monsters you'd captured previously. So any monster you have in your party is at least 10 points weaker in every stat than one you could get if you go back to the exact same place and catch the same monster you found two or three days ago.
It doesn't seem to apply to your "starter" monster or the others you can buy for gems, but it's still enough of a buzzkill that I've mostly lost interest. Just doing the 'farmville' aspects of it so I'll have a large collection of traps and potions if it gets fixed (or if I decide to throw out pretty much my entire collection of monsters and start over).