Did taking Regeneron make Donald Trump smarter? He was a different candidate in this debate, by some way the winner, and it was actually the new format - created to silence him - that helped him.
Threatened with a mute button if he got out of control, Trump stayed disciplined and (mostly) on message. In the first 30 minutes - coronavirus and the economy - he was calm, positive, well-informed and even a little invigorating. Joe Biden faded away, like the ghost of Adlai Stevenson.
That said - in a debate that inverted expectations - Biden had a much better evening when talking about the "moral" issues that can so often be a liberal's handicap. That's because he really cares about them.
He's not a great advocate for healthcare reform (Biden struggled to explain it or sell it) but he got visibly angry, rightly so, talking about the separation of children from their parents at the border.
He found himself on a back foot talking about character, however, because the allegation that his family profited from foreign contacts is starting to break through, even if parts of the US media won't report it. In those moments, the mute button itself seemed muted: things turned nasty, like it did in the first debate.
But it says a lot that Trump complimented the moderator on how well she did her job. There were the usual gross exaggerations from the president, half-truths and all-out lies ("No president since Lincoln has done more than me to help black people"), but Trump is better the less we hear from him and the more he is forced to focus his thoughts.
Without the usual rhetorical violence, a real dividing line emerged between the two men, the issue that this election was always going to be about, dating back to February.
It's the coronavirus, stupid. Biden essentially believes the economy should be shut down if scientists demand it. Trump essentially believes America has to "learn to live with it". If restrictions run too tough for too long, he said, "the cure will be worse than the problem itself" - something Britain is starting to come to terms with.
Millions of independent voters, particularly those with small businesses or employed in the hospitality industry, have got to hear that and think "you know what, he has a point".
From Trump's rare victory of style emerges a narrative for his re-election - late, really late: 50 million Americans have already voted by mail. But better now than never.
The case for Trump is this: you know who he is; you know his faults. But those faults partly come from being an outsider - unlike Biden - and for all his many, many character flaws, Trump does now have a record and he is the candidate who wants to get the economy rolling again.
It was doing amazingly well before coronavirus and you can blame its collapse on China, not him. Perhaps he's the guy to recreate that boom and put the country back on its feet? Many polls still rate the economy and his handling of it, even after months of layoffs.
On the other side, all Biden is really running on is character. "You know me," he said to the camera, "and you know him". That's it. He has a programme - it's quite a radical one - but he's buried his manifesto beneath a landslide of liberal existential pain and golly-gosh nostalgia for an American politics that wasn't.
If you think Trump simply is awful, Biden is the only option to remove him. But if enough voters quietly entertain enough of a suspicion that the president's "not that bad after all", maybe they'll give him four more years.
I had ruled him out. Now, I'm not so sure. Trump won in this debate, maybe he can win in 12 days' time?