The problem with the Chalice items, is that they no longer scale well with missing % of mana, but rather with missing falt amount of mana.
Meaning it's fantastic if you can afford a mana item in adittion.
So along with a RoA or AA/Seraph's it's really good (it helps fill up after abusing Seraph's active as well).
The fact that it scales with amount of mana spent rather than % of mana spent means it's also less effective as the game goes on, since Morello's is 100% mana regen and at low levels Athene's passive needs you to be missing about 300 mana to be worth 50% on it's own.
And guess what, this ineffectiveness increases with level, as your base mana regen scales up faster than how mucch missing mana you can typically comfortably walk around with.
At very high levels it evens out... ish. Or if you get some mana items.
But in general it's regeneration doesn't actually kick in until you're too empty to do anything anyway.
So it aught to be good on poke champions. Or in situations where you can benefit from Athene's other passive.
But Chalice/Athene's is way too weak early game. Crucible is the best mana regen item in the game (since it's got 100% base mana regen plus the chalice passive). But Athene's is too weak as a mana regen item without lots of mana to make up for it by having hybrid stats, especially when the Tear is just as good, grants more AP and is a lot cheaper early game, and Morello's is about as cheap (or cheaper) grants 1/3 more AP, and an anti-healing debuff.
So either get Crucible instead, get some extra mana, or get Morello's.
And then if you need a bit of magic resist in the late game (where you can usually snag at least one kill/assist in teamfights to proc Athene's other passive anyway) You can exchange your Morello's for it.