The dictionary describes an enigma as someone who is puzzling, mysterious or difficult to understand. NHL teams have been dealing with enigmas since the league dropped the puck, and this season is no exception.
Some players have been successful in the past but lost the ability to deliver consistently. Others can look great in one shift and terrible the next. A few seem disinterested or distracted for long stretches.
Their talent got them here, but they are driving coaches crazy. Here are the 10 biggest enigmas in the NHL this season.
Upside: Marc-Andre Fleury was the starting goaltender for a Stanley Cup winner. He's a former No. 1 overall selection in the entry draft and one of the highest-paid goalies in the NHL.
Outlook: The Penguins publicly supported Fleury during the down times, but he has to stand and deliver. His handsome contract expires in the summer of 2015, and he may reach a career crossroads at that time. A strong playoff showing this spring is vital for him.
Upside: Rick Nash is a big skill winger and a natural goal scorer. He currently ranks inside the NHL's top 20 in active career goals and should end up close to 30 again this season.
Downside: He scored 41 goals in his second NHL season and has been chasing that number since. His cold streaks drive fans crazy, and he doesn't provide much else. Nash's game has not progressed and is not refined, so he sticks out when slumping.
Outlook: Ranger coach Alain Vigneault is using him less this season, about three minutes a night on average. The result is a more focused attack, and the goals are coming in fewer minutes. Nash's adapting to the new plan makes for a stronger Rangers team.
Upside: Marian Gaborik is one of the most exciting players in hockey. He is a fleet winger with a natural ability to score goals, and fans love his freewheeling style and highlight-reel goals.
Downside: He can't stay healthy, and it impacts his team in a big way. His salary means he's an important cog in the machine, and his long absences from the lineup can be devastating.
Outlook: He broke his collarbone before Christmas and has been out of the lineup. He may be back in time to play for Slovakia at the Olympics, but the Blue Jackets must clear him to play before he can go. Gaborik's injury track record may make that a bad idea.
Upside: Jason Spezza is a fine playmaking center who has delivered seasons of 80 points or more four times in his NHL career. A power-play dynamo, he is regarded as a quality offensive player.
Downside: He is not fast and has durability issues. This season, he is losing playing time to Kyle Turris. At $7 million a year, he is an expensive second-line center.
Outlook: His skills make him valuable, but it's not a stretch to suggest Spezza wasn't covering his contract before the emergence of Turris. For Ottawa, which is not a cap team, trading Spezza is possible.
Upside: Alexander Semin is a highly skilled winger with great hands and scoring ability. He also has good size and can beat goalies clean with a truly devastating shot.
Downside: He's been wildly inconsistent since arriving in the NHL. His skill level is so good, teams should be able to count on him for 30 goals a season. He is on track for 18 this year.
Outlook: He is signed to a long-term deal with the Carolina Hurricanes. Semin is scheduled to be paid $7 million per season through 2017-18, and the Hurricanes will have a difficult time trading him.
Upside: Jack Johnson is a big, tough defenseman with speed. Scouts love players like him because they possess all the skills and can be effective for a long time.
Downside: Despite all those tools, there's mounting evidence Johnson isn't a good NHL player. The analytics at ExtraSkater.com suggest he has been below 50 percent Corsi for percentage for three seasons in a row, and his offense has taken a significant downturn.
Outlook: He is young, big and fast. Johnson carries a big reputation, so his value remains, and Columbus may end up trading him over the summer.
Upside: Mike Green is one of the best offensive defensemen of his generation. He is already inside the top 20 in career points among active defensemen at age 28.
Downside: Green is a chaotic defensive player and has missed a number of games due to injury in recent seasons. He has played in 163 of the last 262 Washington Capitals games.
Outlook: He is signed for one more year at more than $6 million. Washington has an outstanding young player in John Carlson on the roster. There's a chance the Capitals move on from Green in an effort to cut down on defensive breakdowns.
Upside: Michael Del Zotto is a solid defenseman with very good offensive instincts. His best skill is his skating, and he has very good puck skills.
Downside: There were one dozen defensemen taken in the 2008 draft's first round, and 10 of them have become NHL regulars. Del Zotto is among the group of 10, but he has not progressed like the rest of the group. He showed flashes of his ability, but not consistently enough to impress his coach.
Outlook: The Rangers have been quite public about Del Zotto's shortcomings, and his long-term future does not appear to be in Manhattan.
Update: Del Zotto has been traded to the Nashville Predators, according to Matt Ehalt of ESPN New York.
Upside: Tyler Myers began his NHL career in splendid fashion, winning the Calder Trophy. The big defenseman can impact events at both ends of the ice.
Downside: His game seems to have eroded since that splendid rookie season. Myers has lost confidence and become a chaotic defensive player while also failing to affect the game offensively the way he did in his first year.
Outlook: Buffalo was patient during the previous regime, but new management may decide to move its inconsistent giant.
Upside: Dustin Penner is a big winger with great skills. He can pass the puck very well, is a good shooter and will drive to the new with authority.
Downside: He has a reputation as a lollygagger and a player who doesn't bring his best game every night. Scoring slumps add to the problem, and Penner's long stride often makes him look like he's not working hard.
Outlook: Penner's teams have been successful at most of his stops, so there's no reason to believe it'll end badly in his second tour with Anaheim. Sooner or later, he might even get some credit.