how do you know you've been slapped? you could be dancing. i'm not as experienced as ccarter so bare that in mind. but i've had pages drop out of the top 100 only to come back even stronger.
A couple of things lead me to believe he actually tanked his site.
1. 2000 articles of Spun content backlink to main site.
2. What are the chances he used WordAI, or whatever High quality spinning program? Doubtful, since he has 2,000 versions of the content.
3. Even though Matt Cutts himself said very few people should use Disavow, OP wants to do it - out of laziness. He realizes now he'll have to go to 2,000 websites, delete the content and delete the account, so he asked the question knowing his guy feeling was he was going to have to do it manually.
There is a chance it might be dancing... But I have a feeling this is a small client, probably local business or something that didn't do any vetting of the OP - based off of OP's method of doing "SEO", which is just spam according to him. Usually those websites have less than 100 visitors daily, so 2,000 backlinks from spun content will tank that.
He's lucky he didn't get a WMT notice, cause if that were the case, that means a manual review MAY have occurred. So he still has a chance to clean up his act by manually deleting each backlink and letting the algo adjust itself.
Maybe I'm completely wrong.