While this may ultimately be the case, I'm not sure I agree.
Prior to our run of good play and solid defense, we had no dedicated CDM. Mix and Jacobson both creeped up the field to try to spark attacks. Here's the heatmap from the game against RSL:
You can see that Wingert and Hernandez were largely left without cover, and we lost 2-0.
The next game, against Houston, we drew 1-1. See the difference in the heatmap?
We replaced Wingert in the middle with Facey, but Jacobson also dropped down to shield the backline. I don't think our good CB play was a coincidence. Fast forward a few weeks to the 2-0 win against Toronto, just to illustrate, Jacobson remains shielding the backline and our defense is still playing well:
Following that, we had our only bad game over the last 6 weeks, the 1-3 loss to New Jersey:
There's a few things we did wrong here (look how isolated Villa was, for instance), but one of the big ones was Jacobson abandoning his defensive role. He was right up next to Mix playing around the box. Facey and Hernandez looked excellent against Giovinco and Altidore the week before, and poor against BWP and others the next week. The only thing that changed was Jacobson.
And last week against Montreal, we reverted him back to his place in front of the backline, and we looked great again despite KWS playing, winning 2-1:
Now, I don't think Jacobson is particularly good at his role, but I think it's been very important to our play so far. The least drastic change would be to keep him in the role, with Pirlo free to focus offensively despite a deeper position. There are alternatives, but I hesitate to expect Pirlo to do stuff like chase Giovinco around the field all game like Jacobson did.
EDIT: The drastic solution would involve pulling Jacobson and desperately trying to upgrade your CB spots midseason by pulling unproven players from South Africa and Columbia.
Hmm...