Preseason BPI loves Warriors, IDs Celtics as top Finals challenger

Warriors make the best of free agency (0:53)

After a championship season, Golden State was faced with many big contracts on the line, including Andre Iguodala, Shaun Livingston and JaVale McGee. (0:53)

The 29 NBA teams that are not the Warriors should brace themselves: Their odds of knocking off Golden State are even longer this season. The Warriors have a 57.9 percent chance to repeat as NBA champs, according to preseason numbers from ESPN's Basketball Power Index (BPI). That makes them even heavier favorites than they were this time last year, when they were still the likeliest team to win it all (52.4 percent) by an overwhelming margin.

BPI is a forward-looking model that predicts the strength of each team on offense, defense and altogether. In making its game predictions, the model takes into account factors such as the strength of the two teams, the game's location and rest differential between the two squads. BPI simulates the season 10,000 times to create its projections for both the season and the playoffs.

During the season, the model will adjust daily to include information gathered from every game that is played. But in the preseason, with no games played so far, the model is based on past performance combined with Vegas win totals.

And right now, that tells us ...

The Warriors are really, really good

Breaking news, right? But seriously, it is notable that they are even heavier favorites than they were a year ago. The reason for that is simple: The model, quite frankly, thinks the Warriors are better than it did this time last year. Not better than how they ended up -- that's a different question altogether -- but how good they were expected to be.

BPI believes the Warriors, who are returning all the key players from last season's championship run, are 9.4 points better than the average team. That breaks down to a +5.6 rating on offense and a +3.7 on defense (that adds up to 9.3, but as a result of rounding their total BPI rating is +9.4).

We mentioned earlier that the season is simulated 10,000 times to create BPI's projections. Guess how many times the Warriors made the playoffs in those simulations? Yep, all 10,000. In fact, they never finished worse than the 5-seed in any simulation.

Some other Warriors projections while we're on the subject:

Expected regular-season win total: 63.1.
Chance to be the No. 1 seed in the West: 91.3 percent.
Chance to reach the Finals: 67.2 percent.

Yeah, Steph Curry and Kevin Durant are a tough out.

Their most challenging opponent will come from within the Western Conference: the Houston Rockets, at a total BPI rating of +5.1. That's a pretty wide gap between BPI's No. 1- and No. 2-ranked teams.

Though BPI doesn't specifically make an adjustment for the addition of Chris Paul, Vegas certainly recognizes the impact the star point guard can bring to Houston and adjusts its win totals accordingly, which in turn is reflected in BPI.

But the Rockets are not the second-most likely team to win the title next season.

If not the Warriors or Rockets, then who?

The Boston Celtics, that's who.

That means Kyrie Irving jumped from the reigning Eastern Conference champion Cleveland Cavaliers to the team favored to hold that title next. The revamped Celtics -- with Irving and Gordon Hayward now on their roster -- have a 12.1 percent chance to win the whole thing, best in the East. When the Warriors are taking up such a high likelihood of winning it all, 12.1 percent isn't that bad.

Boston's BPI rating is +4.9, fourth-best in the NBA behind the Warriors, Rocket and Spurs. Despite that, the C's are the second-most-likely to win the Finals because they are in the East.

The Cavaliers, meanwhile, are sixth in BPI (+3.8) and have the fifth-best chance to win it all, at 6.4 percent. The Celtics and Cavs have a 55.8 percent and 27.9 percent chance, respectively, to be the No. 1 seed in the East.

As for Cavs-Warriors IV in the NBA Finals? BPI believes there's a 17.5 percent chance of it happening.

But back to the Irving-Isaiah Thomas deal. How valuable is the Nets' 2018 first-round pick the Celtics gave up?

According to BPI, that pick has an 11 percent chance of being the No. 1 overall pick, a 33 percent chance of being in the top three and a 59 percent chance of being in the top five.

If those are lower than you were expecting, that's because BPI actually doesn't think Brooklyn is the worst team in the NBA. That honor belongs to the Chicago Bulls (-7.2), who dealt Jimmy Butler to the Minnesota Timberwolves this offseason. The Atlanta Hawks, who lost Paul Millsap and Tim Hardaway Jr. and traded Dwight Howard, are the second-worst team in the league at -5.8.

It's no surprise, then, that the Bulls and Hawks also have the best shot at the No. 1 overall pick next summer, with a 20.9 percent and 14.8 percent chance, respectively.

While Boston might keep an eye on the pick it traded to Cleveland, much more important to the Celtics is the Lakers' pick, which becomes theirs if it falls between 2-5 as a result of the trade the 76ers made with the Celtics for the first overall pick in the 2017 draft. That pick has an 18.3 percent chance of falling in the zone that would result in the Sixers shipping it to Boston. The Celtics will receive a different pick in 2019 if the Lakers' pick falls outside that zone.

Who are the big movers?

We already discussed the Bulls and Hawks, the two teams expected to see the largest drop in wins this season. They are followed by the Jazz (expected to win 10.3 fewer games in 2017-18) and Pacers, who each lost a star -- Hayward and Paul George, respectively -- this offseason.

The Timberwolves, who were on the other end of that Butler trade, are projected to win 47.6 games, a 16.6-win increase from their total a season ago. The 76ers are behind them, projected to win 42 games after winning 28 a season ago.

Neil Johnson contributed to this story.

For more from ESPN Analytics, visit the ESPN Analytics Index.