Don't think you read the atmosphere correctly.
It's not whether we have to buy SMS or not - I believe we would get to CL even without him.
But great mezz'ala transfer should have been our top priority since the first day of mercato. I won't criticize F&M anymore, thank god they're gone and they didn't have enough time to operate this summer.
But Leonardo should have been going after a mezz'ala since the day one. Not after Higuain. Not after Caldara. I'm not saying those moves were bad - they're great - but they should have had lower priority than getting a great mezz'ala.
It's like in a role-playing game. You have the main story and other quests to make. Of course you can make those side-quests, you even should accomplish them. But without focusing on the main plot you won't get to the end. And mezz'ala was our main story this mercato.
Without getting a great mezz'ala - Rabiot, SMS, someone unknown, it doesn't matter to me, it has to be a great player - we need a great, big miracle to get into CL. Having even the best striker won't get you anywhere if you don't have a midfield able to pass the ball to him.
That's why I think this mercato will be a failure without a great mezz'ala. I wanted a playmaker and a great winger and what did we get? Castillejo and this Genoa fodder.

And no playmaker at all.
Same happened to Manchester United this winter - they had several great wingers and a weak defence. What did Mourinho do? He bought Sanchez and failed to buy a great defenders. That's why it's said he failed then and that's why I think Leonardo will fail if he won't buy a classy mezz'ala today or tomorrow. It's make it or break it scenario, it's black or white now.