Nov 24, 2014; New Orleans, LA, USA; Baltimore Ravens head coach John Harbaugh walks off the field after their 34-27 win over the New Orleans Saints at the Mercedes-Benz Superdome. Mandatory Credit: Chuck Cook-USA TODAY Sports

Every time the Baltimore Ravens kept the offense on the field on fourth down this season, Twitter exploded. There were always some in favor and some opposed, yet seemingly every fourth down was more controversial than the last. At this point, though, fans should expect it. John Harbaugh has gotten more aggressive with each passing season, and now he is among the most aggressive coaches in the league on fourth down.

It wasn’t always this way. Take a look at the Ravens’ fourth-down performance in the Harbaugh era.

[table id=14 /]

Didn’t expect to see the Ravens a league low in attempts one year, did you? Clearly there has been a shift in philosophy. That Harbaugh has become more aggressive in the past two seasons in not a coincidence, it’s a philosophical shift.

And quite frankly, it’s a good one. There have been a few times that going for it on fourth has bitten the Ravens in the butt. More often, though, it has helped the team win football games, such as a key fourth down conversion against the Miami Dolphins.

John Harbaugh’s fourth-down gamble leads to go-ahead TD — Jamison Hensley (@jamisonhensley) December 7, 2014

At this point, Harbaugh has a pretty consistent philosophy. Go for it on fourth-and-short at the goal line nearly every time such a situation presents itself. Go for it on fourth-and-short when the team needs a jolt offensively. Really, those shouldn’t be as controversial as they are.

That wasn’t always the case, though. In fact, as the table above illustrates, Harbaugh has been among the league’s most conservative coaches on fourth down for most of his career. What changed?

One word. Statistics.

As pure numbers and statistics have washed over the NFL (think Pro Football Focus, Football Outsiders, among others), there is more data than ever before. And contrary to what the Twitterati seems to think, going for it on fourth down is the right call more often than not, as the New York Times broke down.

The impact of going for it on fourth down is actually even more positive than the statistics indicate. Part of the reason the Ravens are so good in the playoffs is because they play with confidence. They believe they can beat anybody, and the coach is the guy who sets that tone. Going for it on fourth down goes a long way in inspiring that confidence.

All told, Harbaugh’s aggressiveness this season paid off much more often than it hurt the team. Harbaugh has been rewarded for his about-face, so expect continued risky calls from one of the best coaches in the league.

Oh, and who led the league in fourth down attempts last year? Marc Trestman’s Chicago Bears. Have fun with that.