Agreed with the group here, with the impact potentially even larger than many suspect. Here's why:
1. Ryan has
zero national infrastructure. The Romney campaign raised a
ton of money, and that enabled them to play in the swing states such that there was a legitimate 1-in-3 chance of the Romney victory as late as October. Ryan will be more dependent on outside PACs (like Karl Rove's Crossroads USA) that didn't exactly cover themselves with distinction in OTL's 2012 campaign.
2. The single best "game changing" moment for Mitt Romney came during the first debate when substantively what Romney did was to jettison essentially his entire campaign to that point and run on a very centrist message. Unlike Romney, Ryan has an unambiguously far-right conservative record; that's great for winning the Republican primaries but makes it virtually impossible for Ryan to pivot in any sort of believable way to the center.
3. Ryan and Rubio both have incredibly thin resumes; Ryan, in particular, has never run a single race outside of his relatively insular R+1 district and its ~300,000 voters. It's not
impossible to be a serious Presidential candidate with just the House of Representatives on your resume, but it's very, very difficult -- and subjectively, Ryan does not pass the gravitas test.
The obvious counter-argument from the Ryan apologists would be 'neither did Obama' -- and to that, I'd say
yes, you're mostly right, with three caveats: (i) winning a Senate seat in a state with nearly 13 million people is more impressive than winning a single congressional district; (ii) Obama made moves to shore up his lack of gravitas in 2008, including most notably selecting Joe Biden as his VP; here, the OP has Ryan selecting a similarly under-qualified running mate in Rubio; and (iii) Obama probably
loses in a neutral election environment (as opposed to a Democratic landslide environment like 2008).
4. Ryan was not an asset as a VP either on the campaign trail or in the vice-presidential debate. Feel free to argue
why, but I don't think anyone can argue that he helped Romney down the stretch. Relatedly: Ryan looked
terrible in interviews everywhere outside of friendly coverage on Fox News, and even managed to flub several high-profile gigs on Fox (including, most notably, the September interview with Chris Wallace).
5. The Ryan budget
polls about as well as ebola.
There's a lot of post-mortems going on about the Romney campaign right now -- some of it deserved. From my perspective, I cannot understand why the Romney campaign declared in August that it was
only going to compete in 9 battleground states (NH, IA, OH, FL, NC, WI, CO, NV, and VA). The major asset Romney had going for him was fundraising; why not at least go up with ads in Michigan, Pennsylvania, Minnesota, New Mexico, and Maine's 1st CD at
minimum and maybe even a few long-shots like Oregon, Connecticut, and New Jersey? All it costs you is money, and
maybe you move the needle some and force the Obama campaign to panic and overreact. As it was, Romney essentially gave Obama 237 EVs out of the box; that's generally not a winning strategy.
Anyway: my point is that while there is a lot to criticize the Romney campaign for, I think it's also easy to overlook that, in general, Romney was perceived as presidential; he (mostly) righted some seriously awful negatives both with the Republican right and with the electorate as a whole; he had a great first debate -- one of the all-
time great performances, by the numbers; and so on. Ultimately, Romney put himself in a position where he had a 1-in-3 shot of being president (according to 538.com) as late as Octoboer, and my guess is that probably represents the ceiling of the Republican field in 2012 with the exception of Chris Christie.