Can you add a photo of the leaves and of the whole plant?

Perhaps some form of S. farinacea or a hybrid? It is hardy to zone 7.

The blooms look like a farinacea (mealycup) but the leaves don't. The leaves and the height look more like a guaranitica but the blooms and calyx don't look like guaranitica. Maybe I'll just call it "Big Blue"?!

The leaves don't look like S. guaranitica to me, more like a broader version of farinacea as far as texture and edges, but I am not seeing it in person, obviously. (I have grown both species as annuals or wintered over potted plants, though neither is garden hardy here.) But the leaves are why I wondered if it might be a hybrid. Hopefully someone else with a broader experience with Salvias will have more solid suggestions.

I have a "Black and Bloom" which is a guaranitica and you're right, the texture of the leaves is different. More of a rough texture. The "mystery" salvia is smooth. This one may winter over only because it is planted next to the house.

It reminds me of my 'Mystic Spires", which is a more compact form of 'Indigo Spires'. Since you say yours is tall and lanky, perhaps its the latter.