Well there's certainly an element of that, and Krotone once held a much larger hegemony over the region, but on the other hand, they're also much less expansionist than Thurii or Rhegion.
They lost 2,000 freemen from the defection of their allies and a further 1,000 in the fighting. They're now down to 6,000, barely enough to even qualify as a middle-tier power.
Good eye. Korinthos' alliance did happen historically and was them explicitly spiting the Spartans by allying with Argos, which was the lynchpin of a series of alliances by which everyone in the Peloponnese who didn't like Sparta allied to Argos, and Argos was allied to Athenai, so the Athenians technically weren't breaching the terms of their truce. Technically.
Though here Athenai hasn't even abandoned Pylos, so who knows if that'll fly.
