The Minnesota Vikings limited the New York Giants to just 10 points in their victory on Monday Night Football. Through four games this season, the Vikings have allowed just 50 points, their fewest since allowing 47 points through their first four games in 1988.

In the 1988 season, they started 3-1 and finished 11-5. The 2016 team is 4-0 through four games.

The defense perhaps also brings to mind the stout Vikings' defense of the late 1960s and early 1970s known as the Purple People Eaters.

They are limiting top quarterbacks

Three of the four quarterbacks the Vikings have faced this season have either won or appeared in a Super Bowl, including the last two league MVP award winners (Aaron Rodgers and Cam Newton). Elias notes that the Vikings are the first team to beat three straight Super Bowl starting quarterbacks (including Manning) since the 2010 Eagles.

The Vikings have been effective when sending additional pass-rushers. On Monday night, Eli Manning was 2-of-8 for 7 yards with an interception against the blitz. The 7 yards are his second fewest in a game against the blitz in the past 10 seasons.

Through four games, Minnesota has held opposing quarterbacks to a 41.7 completion percentage when using a blitz, second in the NFL.

While the Vikings did not sack Manning on Monday night, they have generated 15 sacks against opposing quarterbacks, also second in the NFL (the Denver Broncos have 17).

They are shutting down good wide receivers

Over the past three weeks, the Vikings have faced Jordy Nelson, Kelvin Benjamin and Odell Beckham Jr.

On Monday night, Beckham Jr. was limited to a career-low 23 receiving yards on three receptions.

Nelson caught five passes for 73 yards and a score, but Benjamin was held without a catch on just one target in his matchup against Minnesota.

Beckham Jr. was unable to produce against the Vikings, making all three of his receptions in the second quarter. Manning threw incompletes to him on his last five attempts, including four in the second half.

As a result, Beckham Jr. had his streak of 28 consecutive games with at least four receptions snapped.

Comparison of undefeated teams

There are three remaining undefeated teams: the Vikings, Broncos and Philadelphia Eagles. Each of them features a new quarterback (Sam Bradford, Carson Wentz and Trevor Siemian), as well as a top-five scoring defense.

Bradford is the only quarterback formerly taken first overall with a winning record this season. And he was the only one to win in Week 4. Quarterbacks taken first overall have gone 12-19 this season. They were 1-7 in Week 4.