At 3-0, the Philadelphia Eagles are quickly gaining altitude. FiveThirtyEight’s preseason Elo ratings gave the Eagles a mere 1 percent chance to win the Super Bowl and a 27 percent probability of winning the NFC East; now those numbers are up to 6 percent and 59 percent, respectively.

Three of the league’s four other undefeated teams had much higher preseason Super Bowl odds: Denver was at 11 percent, with New England at 7 percent and Minnesota at 4 percent. Like Philly, Baltimore was at 1 percent — but at least the Ravens weren’t breaking in a new coach and a new quarterback. Philadelphia’s hot start is the one very few saw coming.

Starting 3-0 is typically a very good thing. From 1990 to 2015, 3-0 teams won, on average, 7.7 more games over the rest of the season and made the playoffs 76 percent of the time. But the way Philadelphia has arrived at its record makes the Eagles both worse and better than the average 3-0 team, depending on which lens you view them through.

The Eagles’ new head coach, Doug Pederson, had never held that job at the college or pro level before this year. Quarterback Carson Wentz is a rookie, drafted second overall out of a second-tier program at North Dakota State. Together, they became just the second rookie duo at head coach and quarterback to begin a season 3-0 since at least 1950. The first? That was Rex Ryan and Mark Sanchez for the 2009 New York Jets. Wentz, Sanchez and Greg Cook of the 1969 Cincinnati Bengals are the only three rookie quarterbacks to win their team’s first three games of a season since 1969, regardless of their head coach’s experience.

What does this mean for the Eagles this season? Three teams with rookie QBs are not much of a historical sample from which to draw conclusions, but we can turn to the sidelines and see how 3-0 teams with rookie coaches fared. From 1990 to 2015, 14 rookie head coaches began a season 3-0. On average, those teams played .500 ball the rest of the way and made the playoffs only 57 percent of the time. Compare those numbers with the rates for 3-0 teams without rookie head coaches — a .605 winning percentage and a 78 percent playoff rate — and it’s clear that rookie head coaches are less likely to keep their teams playing well than their veteran counterparts.

But if this year’s Eagles follow that trend, it wouldn’t be all Pederson’s fault. The record for rookie coaches is somewhat misleading, because teams generally change coaches when they have a bad season. And teams that start 3-0 and were bad the previous season are less likely to play well the rest of the season than teams that start 3-0 and have a better recent history. On average, the 131 teams that went 3-0 from 1990 to 2015 had won 9.1 games the season before. But the 14 of those teams with rookie head coaches averaged 7.4 wins the previous year, compared with an average of 9.3 wins the previous year for the other 117 teams.

Not surprisingly, among 3-0 teams, those that were more successful the previous season were more successful over the remainder of the current season:

WINS IN PREV. SEASON NO. OF TEAMS AVG. WINS, REST OF SEASON > 9 64 8.4 8 or 9 32 7.6 < 8 35 6.7 How 3-0 teams closed out the season, by wins in previous year Data is from the 1990-2015 NFL seasons; ties in previous year are considered half-wins. Source: Pro-Football-Reference.com

This is good news for the Broncos, Patriots and Vikings: 3-0 teams that had more than nine wins the previous season won an average of 8.4 games over the rest of the season. But 3-0 teams that won exactly seven games the year before — like the 2016 Eagles — won only an average of 6.8 more games.

So the Eagles fit neatly into the category of 3-0 teams that were both bad the year before and switched coaches. If we exclude the 2009 Colts, 2002 Raiders and 2000 Rams (their coaches weren’t replaced because of a poor record), the other 11 3-0 teams that switched coaches won only 5.9 games over the rest of the year. That would put the end-of-season record for this year’s Eagles at 9-7. This may be a bucket of cold water to pour on Philly’s hot start, but there’s another statistic that should make Eagles fans feel a lot better.

Adjusted net yards per attempt (ANY/A) is my preferred statistic for measuring a team’s passing attack and its pass defense. So the differential between the two is a good indicator of a team’s efficiency. Last year’s Eagles ranked 22nd in ANY/A differential, but this year’s version leads the NFL, thanks to great performances by both Philly’s defense and its Wentz-led offense. The Eagles have been so efficient that Philadelphia is just the 13th team in the era of the 16-game season to win each of its first three games by 14 or more points. Philadelphia is averaging 8.0 ANY/A on offense, third-best in the NFL, and allowing only 4.4 ANY/A on defense, sixth-best, for an overall ANY/A differential of +3.6.

Here’s where the good news comes in for Eagles fans. Historically, a 3-0 team’s ANY/A differential can help us identify whether it’s likely to keep going strong over the rest of the season. Since 1990, teams with an ANY/A differential of between +2 and +5 — the set of teams most like Philadelphia — won an average of eight more games.

By this measure, then, the Eagles are in pretty good shape. And there are reasons to believe the team’s successful ANY/A differential will hold up as the season goes on. For instance, Philadelphia’s defense has been legitimately outstanding, particularly when it shut down the Steelers’ great passing offense in Week 3.

The offense, led as it is by a rookie signal-caller, is of greater concern, however. Wentz has great numbers, but he’s also been placed in generally positive situations. Wentz has had just 13 passing plays while trailing, 20 while tied (all in the first quarter), and 73 while leading, when conditions are more favorable for passing. The Eagles have yet to run a play in the second half without being ahead on the scoreboard, which makes life a lot less stressful for a young quarterback.

Also, Wentz is getting a lot of help from his teammates. According to the NFL’s Game Statistics & Information System, Wentz is averaging 11.7 yards per completion, but 6.2 of those yards have come after the catch. That’s the third-largest average gain after the catch in the NFL, behind only Atlanta’s Matt Ryan (7.1 yards after the catch) and Detroit’s Matthew Stafford (6.2). Meanwhile, Wentz’s average pass has traveled only 6.8 yards in the air, third-lowest in the league, ahead of only San Diego’s Philip Rivers (6.5) and Denver’s Trevor Siemian (6.1). The Eagles are 3-0, but Wentz hasn’t had to do a lot of heavy lifting to get them there.

At some point, Wentz will have taller hurdles to clear, and we can only speculate on how he’ll perform in those situations. But so far, he has exceeded expectations and has been an asset — rather than a liability — on the league’s most efficient team. Wentz’s ongoing maturation is likely to make the Eagles the most interesting of the NFL’s current 3-0 teams to watch as the season goes on.