Top stats to know -- NFL coaching changes

This post will be updated throughout the day as coaching changes are announced.

The day after the NFL season ends often means numerous coaching changes in the NFL and this season has proven to be no different. All day Monday, we will take a look at the coaching changes in the NFL and tell you what you need to know about these changes.

Jim Harbaugh -- 49ers

Jim Harbaugh and the 49ers announced his departure on Sunday night following the 49ers' last game of the season. Harbaugh leaves the 49ers with a 44-20 record, one of the most successful first four years by a head coach in NFL history. Harbaugh’s 44 wins are tied with his brother, John Harbaugh, and Chuck Knox for second most all-time by a head coach in his first four seasons. Only legendary 49ers coach George Seifert won more with 52. Harbaugh’s five playoff wins in his first three seasons with the 49ers are also the most in NFL history.

Jim Harbaugh
Win Percentage as Head Coach

What can the next team to hire Jim Harbaugh expect? Drastic improvement. Each of Harbaugh’s three head-coaching stops has seen him improve the team’s winning percentage significantly from the previous three seasons. The 49ers had a winning percentage of .438 in the three seasons prior to Harbaugh’s arrival and were 6-10 the season before he took over. They improved to 13-3 in his first season and reached the NFC Championship Game. He took a Stanford team that was 1-11 in the season before he became head coach and, in his fourth and final season, led the Cardinal to a 12-1 record and an Orange Bowl win.

Rex Ryan -- Jets

Jets Under Rex Ryan

Rex Ryan was fired by the Jets and leaves the team as the third-longest-tenured coach in franchise history behind Weeb Ewbank and Joe Walton. Ryan’s first two seasons could barely have gone better, as the team was a combined eight games over .500 and reached the AFC title game both seasons. However, the Jets did not finish any of the past four seasons with a record better than .500 and failed to make the playoffs in any of the four seasons. The Jets also forced the fourth fewest turnovers in the league over the past four seasons and had the second most turnovers, a combination that left the team with a minus-42 turnover difference, the worst in the NFL in that time.

One of Ryan’s biggest issues during his six years with the Jets was his inability to get the results he needed from his quarterbacks. Jets quarterbacks never finished a season under Ryan ranked higher than 17th in Total QBR and in each of the past three seasons, the Jets ranked 30th or worse.

Mike Smith -- Falcons

Mike Smith was fired by the Falcons despite being the winningest coach in team history with 66 wins, 17 more than Dan Reeves. Smith, however, is coming off a two-season stretch in which the Falcons were a combined 10-22 and had one of the worst defenses in the NFL.

Smith was 56-24 in his first five seasons with the Falcons, from 2008-2012, the second-best record in the league in that time behind only the New England Patriots (60-20). The Falcons reached the playoffs in four of those seasons and made it to the NFC Championship Game in 2012. However, over the past two seasons, the Falcons were 10-22, the sixth-worst record in the league and the big culprit was the team’s defense. After allowing just 19.5 points per game and just less than 346 yards per game over Smith’s first five seasons, Atlanta allowed an NFL-worst 388.8 yards per game and 26.9 points per game over the past two seasons.

The Falcons also failed to beat good teams over the past two seasons, going 1-14 against teams that finished the season at .500 or better. Only the Jacksonville Jaguars had a worse record, going 0-18 in such games.

Marc Trestman -- Bears

Marc Trestman became the first Bears coach to fail to coach at least three seasons since Paddy Driscoll, who lasted two seasons (1956 and 1957). Trestman’s biggest failing would be the team’s defense. The two worst seasons of opponent points per game in franchise history were the past two seasons, 29.6 last season and 27.6 this season. The Bears also did not disrupt the opposing quarterback much in the past two seasons, finishing 30th in dropbacks disrupted in 2013 and 24th in 2014. A disrupted dropback is when the defense gets a sack, a batted ball, a pass defended or an interception. The Bears were third in the NFL in that category in the season prior to Trestman’s arrival.

Trestman was hired in part for his reputation as an offensive coach and someone who could work with quarterbacks. However, the Bears' offense and Jay Cutler specifically took a huge step back in Trestman’s second season at the helm. After averaging nearly 28 points per game in 2013 and more than 380 yards per game, the Bears averaged just 19.9 points per game this season and 327.1 yards. Jay Cutler finished the season with a league-high 24 turnovers, including 18 interceptions, which tied for most in the NFL. Cutler also saw his Total QBR drop by more than 12 points from 2013 to 2014, going from 66.4 to 54.0, 23rd in the NFL.