The dirty little secret about VP picks is that, usually, they don't matter. You append one relatively-unknown white guy's name to another relatively-better-known white guy's name, and the public yawns and votes however they were already planning to vote.
Of course, sometimes they do matter, some. They might net a few extra points in the VP's home state. They might provide some short-term buzz. But most of the time, when they matter, they hurt, not help, the nominee. They add some sort of circus sideshow to campaign that drags down the actual candidate. Think Palin, or Eagleton.
This is hardly groundbreaking analysis; it's almost accepted as fact in the political world. Which is why most VP picks proceed along the first-do-no-harm principle: someone who is broadly attractive and unobjectionable.
And if you're talking about the optics of Paul Ryan, he's a perfectly decent choice. Maybe he's a little unexperienced, but it's nothing next to Palin. He's certainly a good speaker and a good advocate for Romney. He'll provide a boost in a state where Romney could use a boost.
But there's a problem, and it's a big one. Romney is a man between worlds. His party base continues to fight to tether him to their agenda, while Romney and most political operators seem to know that running on the agenda of the GOP base is not going to win any elections. Simply put, radical cut-it-all-ism isn't terribly popular. So Romney has, up until now, dodged the issue. He's simply avoided taking much in the way of positions at all. Is he a moderate Massachusetts governor who authored the precursor to Obamacare, or is he a Chick-Fil-A scarfing Tea Party figurehead? It's hard to say, and while everybody has their suspicions one way or another, his candidacy created a sort of Rorschach test for policy preferences that ultimately benefited the GOP. Liberals aren't too afraid of him and conservatives think they can keep him in line. It's awkward for the campaign, but it's sort of worked, too.
Well, until now. Because by picking Paul Ryan, Romney has finally taken a side. Ryan's policy proposals dramatically outshine whatever weak sauce Romney has offered thus far; regardless of what Mitt actually endorses, he'll be forever inextricably linked to Ryan's budget. His incredibly, incredibly unpopular budget.
And while VP picks don't matter, policy platforms do.
How could this happen? My guess: 2008 all over again. The Romney team saw they had a boring candidate, but a candidate with the moderate politics most likely to win. They wanted to add some glitz to their campaign; they wanted to up the wattage. So they picked a glitzy, high-wattage VP.
Unfortunately, they're not going to end up with an exciting ticket trumpeting moderate politics. They're going to end up with a boring ticket trumpeting wingnut politics. Just like McCain picking Palin made everyone question McCain's judgment, Romney picking Ryan is going to make everyone reconsider Romney's views. The basic principle of vice presidential candidates remains the same: the nominee is the nominee is the nominee, and everything that happens on the campaign is about the nominee. No one is going to forget that if Mitt Romney wins the election, Mitt Romney will be president. Not Paul Ryan.
Alternatively, maybe they just liked the alliteration.