The Philadelphia Eagles might be underdogs to win the Super Bowl, but they have plenty of believers in Las Vegas bettors, who have loaded up on the NFC champions and caused the line to drop significantly over the first few days of betting.

After the New England Patriots opened as 5.5 or 6-point underdogs on Sunday night, early action drove the line down to Patriots -5 by Monday evening. And it didn't stop there.

The MGM moved the line down to Patriots -4.5 on Wednesday after reportedly receiving a multi-million-dollar bet on the Eagles after previously listing the line as Patriots -5.5. While -5 has largely been considered a "dead number" in the past, meaning that moves across it aren't as significant as other moves across surrounding numbers due to fewer NFL games ending by five-point margins rather than by three, four, six or seven, OddsShark recently wrote about how that's no longer the case, with the percentage of games decided by exactly five points doubling since the extra-point rules were changed in 2015.

According to vice president of race and sports for MGM Resorts Jay Rood, his sportsbook is heavy on Eagles action so far.

"We were getting Eagles action all the way around. So we decided to go down and test the waters," Rood said, per SportsLine. "I was a little surprised to see the public going against the Patriots this hard, but I can understand why they see some value there."  

The MGM isn't the only book to move their line down to -4.5, as the Westgate SuperBook posted a line of Patriots -4.5 Thursday afternoon, per Vegas Insider, as books start to follow MGM's lead from the previous day. The MGM actually adjusted their line to Patriots -4.5 +100 and Eagles +4.5 -120, meaning the juice is on the underdog Eagles and another move down to -4 could be coming soon.

While the line is tightening up, we're seeing the total for the game continue to rise. After opening at 47 or 47.5 at many key sportsbooks in Vegas, the total jumped to 48 at most spots during the week. William Hill quickly raised their total to 48.5 by Monday morning, where it has remained as money pours in on the Over at most books.

One place bettors are starting to find value: the Patriots moneyline. With a team that has plenty of big-game experience but tends to win their Super Bowls by small margins, playing the Patriots moneyline may be the preferred tactic of many bettors, and they're starting to get plenty of bang for their buck.

After the moneyline opened anywhere from Patriots -220 to -250 at most spots (with the number representing what a bettor has to wager to win $100), the constant flow of Eagles money has caused the moneyline drop to Patriots -200 or better at many spots. MGM dropped as low as Patriots -180 at times on Thursday afternoon, per Vegas Insider, while the Westgate was dealing Patriots -190 after moving their pointspread line down to Patriots -4.5.

What will be the breaking point for bettors as they look to play by the Patriots laying the points? We have roughly 10 more days to find out.