Who are the best caddies in golf, and what makes them great?

— -- This is the hardest thing I've ever had to write. I thought it would be fun, easy and informative for the fans.

The assignment? Ask my friends and former colleagues who carry the golf bags of top golfers who the best caddies working today are.

Some of the initial responses:

"I'm not doing that."

"Why would you ask a question like that?"

"Me, me, me, me and me. Can I do that?"

There was one running theme from every caddie.

"The key to being a good caddie? Go to the first tee with a top player."

The best analogy?

"A great jockey can win the Kentucky Derby on a thoroughbred. No matter how great the jockey is, if you go to the starting gate riding a donkey, you ain't winning s---."

My counter to all those arguments was the same.

"True, but does [name deleted] win without [name deleted] on the bag?"

There were countless examples of donkeys. That caddie admitted, "You got me there."

I even got a funny answer from a multi-major-winning player when I texted him.

"What makes a great caddie? Answer: a great player. I won with [name deleted] on the bag. That ought to tell you something!"

But when pressed, he texted back, "Trust, knowledge, and maturity" makes a great caddie. Then a minute later, he added, "And thick f---ing skin."

Here's what really makes a great caddie:

Trust. Does the player know with every fiber of his or her being that the caddie is giving the best information possible? When players aren't sure what to do, they have to be able to trust their caddies to know their game well enough to give them the best opportunity for greatness.

Honesty. Players don't like hearing they're wrong or they're getting bad advice from someone close to them (i.e. a swing coach, sports psychologist, girlfriend/boyfriend, etc.). A great caddie is willing to say the things most people around a golfer won't say.

Positivity. All golfers go through lows in their game. They get down in the dumps and have a tough time getting out. It happens often on the course and can even surface during a good round. The best caddies exude an air of positive confidence that makes players feel that even when they're not at their best they can be successful.

There are many great caddies on both the PGA and European Tours, but these five were mentioned more than any others when I asked: Who are the top five caddies in the world?

1. Steve Williams: This man is on pretty much everyone's list of best caddies, even from guys who don't like him. "Personally I can't stand the guy, but his record stands alone. He's won with everyone," one caddie told me. (Williams is known for caddying for Greg Norman, Raymond Floyd, Tiger Woods and Adam Scott, among others.) If there were a caddie draft, Williams would be the No. 1 pick. What makes him a great caddie? No moment is too big. If he thinks you're wrong on club or line, he'll let you know without hesitation or doubt in his voice.

2. Jim "Bones" Mackay: The epitome of "going to the tee with a great player" holds true in the case of Phil Mickelson's longtime sidekick. But a caddie I have the utmost respect for told me Mackay "should go into the [Hall of Fame] when Phil goes in because without Bones, Mickelson would never have become the golfer he is today." Can you hold it against a guy for having the same boss for the past 24 years? Most caddies I asked didn't. They considered it a badge of honor instead.

3. Mike "Fluff" Cowan: He has been caddying for more than 40 years! The past 17 years were for Jim Furyk. Of course he became famous as Tiger Woods' caddie from 1996 until being fired in 1999, but he's also carried the bag for Michelle Wie and Lydia Ko. Cowan is widely respected by caddies for his laid-back nature and humor. A very good golfer in his own right, he's a member at Congressional Country Club.

4. Mark "Fooch" Fulcher: People might think his success has only recently happened with Justin Rose. They'd be dead wrong. Fulcher has been on the bag for a world No. 1. That was in 1994, and the bag belonged to Laura Davies. Part of what makes Fulcher such a great caddie is what that other major winner said in his text to me about thick skin. Rose is a great player, and it took a great caddie to bring it out of him. He and Rose have been together for eight years.

5. Zack Rasego: Here's something you don't hear every day: In 2010 on the Monday of The Open at St. Andrews, Louis Oosthuizen told Rasego he'd be fired at the end of the week. Rasego would just caddie carelessly that week then, right? Not so much, because they won! Rasego won 2012 European Tour Caddie of the Year with Branden Grace, who then fired him.

What's the biggest compliment a caddie can get from a player after being fired?

"I made a mistake, but now I have corrected it," Grace said after rehiring Rasego. They won shortly after being reunited and haven't stopped winning since.

Honorable mentions: Alistair "Squirrel" Matheson, Paul Tesori, Damon Green, Jimmy Johnson, Gareth Lord and Travis Perkins.