What's in store for golf's future?

The 2013 PGA Tour season had four different major winners and 31 different regular event winners. Tiger Woods added five victories to bring his career total to 79, three short of Sam Snead's record of 82.

Phil Mickelson finally broke through in the Open Championship, the one event he seriously doubted he would ever win. A 19-year-old kid from Texas, Jordan Spieth, became a full-fledged superstar in one year, giving us perhaps the best season by a rookie since Tiger Woods in 1996.

By late summer, Henrik Stenson was the best player in the world.

Jack Nicklaus was right last week when he said that we have as many good players as we have ever had in the game. This season was a testament to that assertion.

Yet the year also left me with some lingering questions. Here are five I'll be mulling for the next few months.

1. Rory McIlroy's audible
The most baffling aspect of McIlroy's 2013 season isn't that he made wholesale changes to his golf equipment after rising to No. 1 in the world ranking a year ago. It's hard to scold him for taking Nike's money and joining the global sports marketing machine.

What's more disconcerting is how a player of his caliber couldn't adequately adjust to the new gear and the heightened pressure to win at least one worldwide event, or show consistent flashes of the brilliance that led him to 8-shot wins in two majors.

It's one thing to not win but still have several top finishes, but McIlroy didn't even make the Tour Championship.

Will he ever be as good as he was in 2012, when he won five times worldwide? Can he again separate himself from the game's elite in much the way Tiger has over his career? What will the 24-year-old Northern Irishman do to right his way in what has still been a very brief career?

He has the remainder of 2013 and next year to answer these questions.

What's unmistakable is that his confidence has taken a major hit in the past 10 months and that he has a lot of work to do to regain his place as the No. 1-ranked player in the world.

2. Major headaches for Tiger
For nearly 20 years, Tiger Woods' name has been synonymous with major championships. From that first historic Masters win in 1997 to his heroic victory at the U.S. Open in 2008, Woods has done perhaps more than even Jack Nicklaus to raise the public's fascination with the big four.

Yet, for Tiger, the quest to break Nicklaus' record of 18 majors must sometimes feel like a heavy burden. This pressure was evident in 2013, when he won five regular events but didn't perform close to that level in the majors.

How long will this drought continue before he goes off looking for answers in a new swing instructor?

Tiger is one of the most restless tinkerers of his generation. He won't sleep well until he solves the mystery of the full swing and the short game. Earlier this year he got some helpful putting hints from semiretired, Steve Stricker, who, by season's end, was playing much better golf than his pupil.

Sean Foley has been a very attentive teacher for Woods despite a stable that now includes Justin Rose, Hunter Mahan and Lee Westwood. Foley has bandaged some of the wounds left by Hank Haney, but Tiger still regularly fights his golf swing, particularly with his driver. Struggles with short putts hurt him all year in clutch situations.

Yet Woods returned to No. 1 in the world and likely will break Snead's career wins record by the end of the spring.

But will anybody take notice of this monumental achievement if one of the victories isn't in a major?

3. No rocking chair for golf's hardest-working man
New York Yankees closer Mariano Rivera is retiring this fall after 19 years in the big leagues. At ballparks across the country, he's been given a hero's sendoff.

Golfers don't get motorcycles and rocking chairs when they retire, in part because, with the Champions Tour, they never really stop playing.

Last week, Vijay Singh made his Champions Tour debut at the Pacific Links Hawaii Championship, where he finished in a tie for sixth. It's uncertain what his long-term plans are for the senior circuit, but what's clear is that he didn't have an easy passage to 50 in 2013.

For a World Golf Hall of Famer with 34 career wins, including a Masters, two PGA Championships and a nine-win season in 2004, you hope for a nice transition to the next phase of his career. Instead, the hard-working Fijian had his worst year since joining the tour full time in 1993, earning no top-10s and just $309,351 in 19 events.

As a mainstay of the first eight Presidents Cups, an appearance at Muirfield Village, where he won the Memorial, in this year's edition of the biennial matches would have been a fitting way for him to end his match-play days.

But mostly what we will remember about perhaps Singh's last full season on the regular tour is that he sued the PGA Tour for exposing him to "public ridicule and humiliation" over his admitted use of deer-antler spray, which contained a minimal amount of the IGF-1 factor, a human growth hormone. The PGA Tour had suspended Singh but reversed course after the World Anti-Doping Agency said deer-antler spray no longer was considered a prohibited substance.

Regardless of the outcome of the suit, it's not a good day for anyone in the game when one of its greatest inspirational stories is mired in controversy.

Sure, Singh will continue to play in the Masters and the PGA and wherever else he wants to go, but we're not likely to see the Singh who won 22 events after he turned 40.

What will be his lasting legacy after what transpired in 2013? My hope is that he will be best remembered as one of the hardest-working players of his generation and the best ever in his 40s.

4. Lefty's Open
Mickelson is 43 and still easily one of top players in the world. We saw that brilliance in full during his win in July at the Open Championship at Muirfield.

All he needs now is a U.S. Open to complete the career Grand Slam. At this point of his life, getting that championship is more pressing than the addition of another green jacket or PGA Championship.

Come June at Pinehurst, where he famously finished second to Payne Stewart in 1999, Mickelson will have a chance to fulfill that career goal. Pinehurst won't be his last opportunity at an Open, but, with him turning 44 the Monday after the tournament, his time could be running out to take what is arguably the hardest event to win.

Hale Irwin became the oldest U.S. Open winner when, at 45, he took the 1990 championship at Medinah.

What kind of start will Mickelson have to his 2014 season with Pinehurst at the forefront of his thoughts? He's bound to build his year around this one event.

5. Rules officials
Do you want a man or woman sitting on his or her couch with a decent handle on the rules of golf and an HDTV to have the power to call in rules infractions on tour players?

This is a question the PGA Tour is seriously pondering after a couple of episodes this season involving Woods. Dave Eger, a Champions Tour player and former tour rules official, famously called in Tiger's bad drop on the 15th hole of the second round at the Masters in April.

Then, two weeks ago at the BMW Championship, a PGA Tour Entertainment videographer captured Tiger's ball moving as he tried to move some loose debris.

Woods wants a time limit placed on viewer call-ins. The tour wants to study the issue more. For the time being, we're likely to continue with those TV viewers eager to play a game of gotcha to uphold the rules of golf.