1) Cruz is well-positioned in the polls for when the field whittles down
The picture regarding who will be the Republican Nominee remains as unclear as ever, with 15 candidates still in the race. The crowded field has worked to the advantage of outsiders, whose pitch is that bit more interesting and newsworthy than conventional politicians. Donald Trump, Ben Carson and Carly Fiorina took out over 50% of the latest Fox News poll.
For the other 12, just being noticed has been a challenge and very soon, around half that number are going to find it impossible. For the next CNBC debate, the main podium will be restricted to candidates averaging over 2.5% among six pollsters, between 17th September and 21st October.
Only six are comfortably above the threshold, and the likes of Mike Huckabee, Rand Paul, Chris Christie and John Kasich are all flirting with relegation to the minor stage. At 10% in that latest Fox survey, Cruz has no worries and will be one of the six that are likely to dominate thereafter.
2) He appeals strongly to the Tea Party, social conservatives and other insurgents
As the crisis following John Boehner's resignation as Speaker illustrates, the Republican Party is deeply split. As on other issues, the Texas Senator has led the insurgency in Congress and, while that has alienated many 'mainstream' Republicans, much of the base adores him.
He recently won the Voter Values Straw Poll for the third straight year, confirming his strength with social conservatives. At the weekend, Cruz topped a state-wide Tea Party caucus in North Carolina.
3) Cruz has all the resources required to fight a long, hard race
That sort of enthusiasm and support from the grassroots will be critical. To accumulate caucus votes, you need both political skill and troops on the ground. In addition to those traditional tools, digital campaigning will play a key part in this election. Cruz is thriving in this sphere, perhaps even winning the battle.
You also need money. Lots of it. Most campaigns will disintegrate if they're not immediately competitive in the early primaries but Cruz has plenty to sustain a full bid. He's already raised more than $50M and is well placed to tap more from sympathetic mega-donors like the Koch brothers or Club for Growth.
4) He is the most obvious recipient, should the non-politicians fade
With 10%, Cruz was the leading politician in that latest Fox survey behind Trump and Carson. While those two outsider bandwagons are still running, doubts persist about their staying power. Should either or both slip back or even withdraw, Cruz is the likeliest beneficiary.
The key distinction between Cruz and the other leading politicians is his rebellion in Congress, placing him closer to the insurgents than the mainstream. Plus while the rest attack Trump, Cruz has been supportive and stated his expectation that Trump voters will eventually end up with him.
5) At 4% just to win the nomination, Cruz offers a cheap back to lay trading opportunity
At this early stage of the race, think less about the eventual winner than the short-term trajectory of the market. Cruz may well be too radical, too conservative to ultimately win the nomination. Mitt Romney may well be right to define the race as 'mainstream' versus 'insurgents', including Cruz in the latter while predicting eventual victory for the former.
Nevertheless before that is resolved, this market will transform into a small contest between no more than five or six candidates. By the end of February it will be two or three. Even at the first stage, his odds will almost certainly be shorter. Where's the risk?