Scott Walker had a very, very bad campaign.

He's now dropping out, so that statement, on its face, seems obvious. But there's a reason for the replication of those "very"s and the reference to his campaign, not to the election or to 2016.

Walker, like many other candidates, saw a bump in the polls shortly after he announced. But the top of that bump wasn't as high as his poll numbers had reached earlier on either nationally or in Iowa, where he was consistently the front-runner for months. He announced, he got the bump -- and then it vanished.

The vanishing, it's worth noting, happened shortly after the first debate, in which Walker offered an unimpressive performance.

That sort of erosion isn't as common as it seems. Rick Perry saw it in 2012. Rudy Giuliani saw it when the bottom fell out in 2008. Usually, fade-outs are less steep and more extended. Walker plummeted.

Since his announcement, Walker saw an 81 percent drop in his Real Clear Politics polling average -- and he was the second-to-last major Republican to announce.

Or, put more succinctly: Scott Walker had a very, very bad campaign.