It was a banner today for Rory McIlroy and Nike as the two announced a partnership that ties the world’s No. 1 golfer to the world’s top shoe and apparel brand, but the most intriguing questions went unanswered at the news conference in Abu Dhabi Monday morning.

The essential ones:

How much is the deal? And does Rory HAVE to play Nike clubs?

Although Nike officials, in typical fashion, wouldn’t disclose the terms of the contract, I was told there’s no way it’s for the $250 million some outlets have reported.

The second question is the more intriguing one.

Although it was a great marketing tool, the fact that Tiger Woods’ contract specified he didn’t have to use Nike equipment had to be uncomfortable. They paid Tiger all this money, and if things went wrong with his game and he made some changes away from Nike clubs, all momentum for that product would’ve sputtered.

I always believed Tiger would be an exception to the rule for this. Nike couldn’t be in the habit of saying, “Use what you want.” No one in all of the sports marketing world does this. You get paid for a reason -- to play with a product or wear a company’s logo.

In fact, besides Tiger, there’s only one time in Nike’s history that I recall the company allowing its endorsers to use something other than what it made: The 2008 Olympics. As the buoyant Speedo suit was clearly so far ahead of its competition, Nike -- as well as other companies -- thought it was better to allow its athletes to win in Speedo than not win at all. It was a hard admission for Nike to make. Although the company sells plenty of Air Force 1’s, Nike takes so much pride in giving its athletes the best chance to be great at what they do.

Equipment is a huge part of the game. It’s why athletes often leave money on the table to wear or play with a certain brand. Pete Sampras insisted on playing with the same Wilson profile.

It’s in tennis where you see athletes shift to a brand and then have regret. Both Maria Sharapova and James Blake signed lucrative deals with Prince, only to undo their deals when they were uncomfortable playing with the latest racket technology that Prince made them use.

On Monday morning, McIlroy refused to answer if he’s allowed to use non-Nike clubs, which suggests to me that he can’t. Nike did a good job marketing the fact that Tiger didn’t have to use their clubs and ball and for some consumers, it helped Nike’s credibility in the golf space that he did put the swoosh in his bag.

But a company with the pride of Nike, which publicizes its innovation proposition, can’t have guys using its competition, especially in golf, where golfers’ clubs are categorized and publicized with each tournament.

In a skeptical world, athlete endorsements are a challenge for society. Are they less effective because it’s a paid deal? Do you believe that an athlete would be wearing or playing with a specific brand if he or she wasn’t getting paid?

Some athletes who struggle with new equipment fake like they’re using the latest and greatest from the company that pays them. With the company in on the deal, tennis players often have put $15,000 paint jobs on their rackets to make it look like they are using something they're not. Because of the scrutiny, Nike won’t be able to do that with McIlroy if he struggles. Sure, his clubs can be fitted to his exact specifications -- few pros are playing off-the-rack clubs, anyway -- but there will be keen eyes on what he pulls out of his bag.

Nike knows this. In 2000, a public advocacy group sued Nike because Tiger was pitching the “Tour Accuracy” ball, but admitted to using custom balls. Six months after the suit, Tiger’s ball -- with a slightly harder inner and outer core -- hit the market. If Rory can be his same old self or better using Nike products, this will be a tremendous deal for both parties. But what if he struggles? Can he put his old clubs back in play and still collect a check from Nike?