It's been a whirlwind three weeks in the 2016 game.  We went from zero announced candidates March 22 to four announced candidates — including someone you might have heard of named Hillary Clinton — on April 14. Speeches have been delivered. Videos have been released. Logos have been debated.  The race is on.

So, what do we know today that we didn't back on March 22? Ok, I'll start. Here are five things I know today — or at least have more clarity on — than I did three weeks ago.

1. Hillary Clinton still isn't a great candidate.

Look, if you are a betting person, the former secretary of state has — and should have — the best odds of being president.  But she is not now nor ever has been anything close to a natural as a candidate.  In the video released by her campaign Sunday, which Ruth Marcus pans here, Clinton comes across as wooden and unconvincing in trying to show she is just one of the regular folks. And, as Dan Balz so perfectly outlined in a piece over the weekend, we still don't have a "why" for Clinton's candidacy — a governing philosophy or even a few specifics on what she would do if she got the job she's now running for again.

Clinton may not have to be a superstar candidate to get elected president. And, she will have some months here with only nominal primary opposition to polish her skills on the stump. But the truth is that she is never going to be the sort of charismatic candidate that the American public likes to fall in love with during election season. This week reminded me of her struggles to connect in 2008 all over again.

2. Ted Cruz is a better candidate than you think.

Out of the four announcements we've seen, Cruz's came off the best.  He was the first candidate to announce — on March 23 — and got a week's worth of very favorable publicity around that announcement.  Not surprisingly given all that attention, the Texas senator immediately saw a major leap in his poll numbers. Just as importantly, Cruz came across as more three-dimensional — in a good way — than he has been portrayed (and allowed himself to be portrayed) in the media up to this point.

Cruz will always be the most conservative candidate in the field and, as such, will inspire plenty of loyal followers and lots of loyal haters. But what his announcement week proved is that he will not so easily be pigeonholed as a fringe candidate as some Republicans seem to believe. He has some moves.

3. Rand Paul has a media problem.

For months (and months) the Kentucky senator's likely 2016 rivals griped behind the scenes about the positive coverage he was receiving. And he did get some favorable coverage.

But as the past 10 days revealed, Paul's media honeymoon is over.  He clashed with NBC's Savannah Guthrie, got into an abortion back and forth with an AP reporter and just generally distracted from the topic at hand, which was his just-announced presidential candidacy.

Paul's struggles to get his interactions with the media even close to right in the early days of his campaign exposed a broader issue for him: At times, he seems to be operating as though the campaign is a lecture he is delivering to an adoring group of undergrad political science and philosophy majors rather than a conversation and debate between himself, the other candidates in the field, voters and, yes, the media.

4. Marco Rubio isn't going to pull punches on Jeb.

In Rubio's announcement speech Monday, he made very clear that Jeb Bush, his one-time mentor, was very much fair game in the campaign to come. While Rubio didn't mention Bush by name, the echoes of the Bush-as-too-old-and-with-old-ideas attack to come were everywhere.

Here's Rubio's most telling passage — one that doubles as a two-for-one shot at Jeb and Hillary:

Yesterday is over, and we are never going back. We Americans are proud of our history, but our country has always been about the future. Before us now is the opportunity to author the greatest chapter yet in the amazing story of America.
We can't do that by going back to the leaders and ideas of the past. We must change the decisions we are making by changing the people who are making them.

Leaders. Of. The. Past. Rubio clearly understands that his path to the nomination — like every other Republican's path to the nomination — goes through Jeb and that he, at least, isn't going to be afraid to take a swing at the biggest guy in the yard.

5. Candidate committees are dead. Super PACs killed them.

Remember that I said that some of these lessons are things I RE-learned over the past three weeks.  So, yes, I knew that the ability of a single donor to write a massive check to a super PAC supporting a candidate was a big deal back in the 2012 cycle. But the candidacy of Rubio, in particular, speaks to just how much the campaign finance landscape has been changed by super PACs.

As recently as the 2008 campaign, a candidate like Rubio wouldn't have run for president — because he couldn't raise the money. With Jeb hoovering up much of the cash that would go to Rubio in a Jeb-less field, there just wouldn't have been a plausible path open to Rubio. He almost certainly would have been forced to the sidelines to wait until the next time the Republican nomination was open.

No longer.  Rubio's super PAC, Conservative Solutions, which is being seeded by a handful of very wealthy individuals, will carry the financial heavy lifting (read: TV ads attacking his rivals) of the campaign, allowing him to run a more lean, light (and less well financed) campaign. How much money Rubio raises into his official presidential campaign committee is sort of besides the point.