Consensus is a word that should be used carefully when you talk about the NBA draft.

Occasionally a prospect emerges who is so clearly better than anyone else in the draft (see Anthony Davis in 2012, Blake Griffin in 2009, LeBron James in 2003, Yao Ming in 2002, Tim Duncan in 1997, Shaquille O'Neal in 1992), but more often, if you put 10 GMs into a room and ask them who the best player in the draft is, you'll get three or four answers.

This year is no exception. With less than a week to go before the draft, the Minnesota Timberwolves are debating whom to take at No. 1 -- Karl-Anthony Towns, Jahlil Okafor or D'Angelo Russell. If the Wolves, who employ dozens of full-time pros who work at this all year, can't figure it out, how can we create a consensus ranking?

We want to believe that there's a Big Board in the sky that knows all. It doesn't exist. Reasonable minds can differ on prospects, and as much as we all love ranking players 1-100, it's not the best or most preferred way to do it.

This year, five players have a case to be picked No. 1 -- Towns, Okafor, Russell, Emmanuel Mudiay and Kristaps Porzingis.

Whom do you choose to draft? And how?

NBA teams watch prospects play thousands of hours of games. They go to practice and camps. Hire guys from MIT to create statistical solutions. Work out players, give them psychological tests, do background checks and conduct personal interviews. And, still, there is very little consensus.

Factor in the debate between taking the best player available and which player a team needs most, and the situation further muddies itself.

To make sense of all this, the past few years I've chronicled a draft ranking system called the tier system, which several teams employ.

By this method, teams group players into tiers based on overall talent, then rank the players in each tier based on team need. A more detailed explanation of how the system works can be found here.

So how do things break down? After I talked to several GMs and scouts whose teams employ this system, here is how the tiers look this year.

Players are listed alphabetically in each tier.

Tier 1

Karl-Anthony Towns, F/C, Kentucky

Note: Ahead of last year's draft, we had three players in this category: Andrew Wiggins, Joel Embiid and Jabari Parker. This category usually is reserved for guys who are sure-fire All-Stars/franchise players. Just three other players since we started this column in 2009 -- Griffin, John Wall and Davis -- have been ranked in this slot. You have to be elite to get here.

This year was one of the toughest yet. Five players were nominated for Tier 1 by various teams. However, only one player was consistently mentioned by all of them: Towns. While some teams don't see major separation between him and the players in Tier 2, others feel there's a gap and he's the only one in the draft who has the potential to be a franchise, top 10 player in the league guy.

Tier 2

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Emmanuel Mudiay, PG, Congo

Jahlil Okafor, C, Duke

Kristaps Porzingis, F/C, Latvia

D'Angelo Russell, G, Ohio State

Note: This is a very strong Tier 2. Mudiay, Okafor, Porzinigs and Russell all have a claim to the No. 1 pick. In fact, Okafor was the favorite to be the No. 1 pick since July and several teams put Russell on par with Towns. Both received votes for Tier 1, but not enough to move them up.

Tier 2 is reserved for players with All-Star potential. However, each player on the list has a weakness that some teams feel will keep them from being a superstar. For Mudiay it's shooting. For Okafor and Russell, it's athleticism and defense. For Porzingis, it's a thin body and questionable position. Nevertheless, all four have strengths that should propel them to an All-Star game at some point in their careers.

One fun note: Last year we did the column before Porzingis had withdrawn from the draft. He was regarded as a Tier 4 prospect last year. So he's jumped up two tiers.

Tier 3

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Willie Cauley-Stein, F/C, Kentucky

Mario Hezonja, G/F, Croatia

Justise Winslow, G/F, Duke

Note: This is a very strong Tier 3, as well. Both Hezonja and Winslow received Tier 2 votes from teams. However, both fell just short of the cut.

This tier usually is reserved for players who are projected as NBA starters in their careers. All three of these players should be gone in the Top 10. Hezonja, especially, has some star appeal, as well. Having eight players in the first three tiers makes for a very strong draft, but not quite as strong as the 2014 draft that had 12 players in the first three tiers.

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I love this way of evaluating players. Really puts things into perspective. It shows we are in a great spot in pick 4. After Towns, the next 4 players are relatively equal, all things considered. We will have the ability to pick from 2 of them. Plus, Winslow did receive Tier 2 picks, just not enough to make the cut. Shows that some people do believe he has some all-star upside, not as much as the others, but with his low-risk downside, it's not a bad combination.