I don't know what Mikko's agent's last offer was, but in general I think it made sense to expect a long game given the the Avs took it to the wire with Landy. And they went into camp without a deal with Mikko last time.
Though Aho I believe said he texted Mikko a few days prior to ask if he could be traded, and I think he said it was a possibility.
If true, then that's the point his agent should have just made the $12.6M offer. Who knows if he did.
My guess all along though is the Avs are never really that serious about signing him for more a number that didn't start with 10, and they didn't think Mikko would take that given the market, so there was a lot of gamesmanship on both sides.