Yesterday, I suggested there were some clues pointing to Virginia Gov. Bob McDonnell (R) as Mitt Romney’s VP pick. There might be clues leading to other figures (e.g. Mitt Romney will be in Ohio next week, Sen. Rob Portman’s stomping grounds). Anyone in the party or pundit class trying to influence the pick is probably barking up the wrong tree. The Romney team has controlled this process tightly from the get-go, and there is not, I am certain, a pro and con argument the team hasn’t heard.

But a number of readers were puzzled: Why McDonnell? Rather than make the case for him, let’s look at how Romney, the only voice that matters, would see him and another frequently mentioned contender, remembering that Romney likes to gather a bunch of data and then make a decision. (Don’t expect any flights of fancy on a decision as big as this.) He and his staff know that while the pick itself might not win or lose the election, the rollout will be a critical moment when the undecided, relatively less-engaged voters perk up. So the presentation and initial impression are key.

This means Romney is unlikely to choose anyone who hasn’t already been “road tested” as a surrogate and been interviewed by national media. He’s going to want to pound home his theme that he’s the experienced executive who has figured out where President Obama has gone wrong, is going to set aside Obama’s collectivist ideas and can revive the economy. He won’t want to wig out the base (the reminder that former Minnesota governor Tim Pawlenty has a tax hike in his record might be a signal to TPaw fans that while innocuous, Pawlenty opens up a can of worms about Romney’s own conservative bona fides.) But he has to keep independents in the fold.

McDonnell resisted all entreaties to raise taxes as governor. He stuck to his game plan, namely make the state business friendly, balance the budget and reform government. All of this will have impressed Romney. McDonnell has worked rather well with Democrats, who only this year tried to test him with a budget stand-off. McDonnell favors bread-and-butter issues, eschewing red meat during his own race. He made a point of criticizing the president’s policies (and running against them) in 2009 without making it a race against the president personally. That’s pretty much what Romney wants to do this time around.

Rep. Paul Ryan (R-Wis.) is another top contender, and for good reason. He and Romney have worked closely on the same set of policy ideas and the identical message, giving voters a choice between Obama’s dependency society and Romney’s opportunity society. Where Romney has needed help — putting meat on the policy bones and crafting rhetoric to put those policies into a big picture — Ryan shines. Ryan also has spent a couple of years battling, ferociously, against Obama’s policies and spin. He does it with arguments and data, just as Romney prefers.

McDonnell as VP doesn’t mess up the Romney message. He’s experienced (as a legislator, attorney general and governor). He’s an executive. He’s not from D.C. He has no connection to the Bush administration. He’s a conservative reformer, not a libertarian, on one hand, or a big spender, on the other.

He’s called “bland” by some political observers, but this is not a four-letter word in Romney country. Moreover, he gave one of the better State of the Union address responses in recent years, suggesting he knows how to project some gravitas.

Ryan as VP enhances the message. He’s experienced as well and has pulled together a conservative agenda and budget, just as the Romney White House would need to do. He has no connection to the Bush administration and to a large degree challenged the entire GOP establishment. He is the quintessential “young gun” reformer.

He’s too wonky for some, but that razor-sharp intellect suits Romney just fine. He gave another State of the Union address response, showing he can put the details of a budget into an uplifting message

Certainly there are other candidates with different virtues. Portman would help in a key state and reinforce Romney’s center-right ideology. New Jersey Gov. Chris Christie has a working-class persona and the experience of getting things done with an overwhelmingly Democratic legislature.

In the end, however, Romney will choose someone who he is convinced can withstand scrutiny and who, maybe more than anything else, he respects and feels comfortable with. Whether that makes a candidate “safe” or not is in the eye of the beholder, but Romney isn’t likely to choose an inexperienced or an erratic candidate, and he sure isn’t going to pick someone who’s a stranger to him or the campaign.