There are always a ton of great storylines to follow each NFL season, and bettors need to do their best to keep up with all the changes. For 2021, one of the biggest stories will revolve around the array of rookie head coaches who will be pacing the sidelines.

There are six in all — Robert Saleh, Jets; David Culley, Texans; Urban Meyer, Jaguars; Brandon Staley, Chargers; Arthur Smith, Falcons; Nick Sirianni, Eagles. That doesn’t include the Lions’ Dan Campbell, who was interim coach of the Dolphins for 12 games. Six first-time coaches ties for the highest number in any year of the past decade. Here are a few rookie coaching systems to keep an eye on:

Of the 34 rookie head coaches who inherited teams that finished under .500 the previous season, 26 led their teams to better records the next season. With all six of this year’s new hires taking over teams that were 7-9 or worse, that would mean four or five of the teams figure to improve. If the number is four, my guesses would be Atlanta, Jacksonville, the Jets and Philadelphia.

Of the eight rookie head coaches over the past 10 seasons who inherited offenses that scored at least 23.5 ppg the previous season, the team of only one produced a worse record the next season. The others improved by about 2.5 wins per season. The new coaches taking over competent 2020 offenses are Smith, Culley and Staley.

There has been a lot of room to grow when a new head coach takes over a team that scored fewer than 18 ppg the previous season. There have been immediate results for this lucky group of coaches, as nine of 10 teams that fit this bill over the past decade have improved, by an average of 4.9 wins per season. The coach looking to continue this trend is Saleh with the Jets.

Point differential has also proved to be a good indicator of potential improvement as the last 10 rookie coaches to inherit teams that were outscored by 8.5 or more ppg have brought instant change to their clubs. All 10 improved their franchise’s win total that first season, by an average of 4.8 wins. For 2021, we have two candidates: Saleh and Meyer.

As far as in-season game-by-game betting opportunities, it should be noted rookie head coaches have produced a regular-season record of 302-353-1 SU and 322-313-21 ATS over the past decade. In other words, they lose more than they win on the scoreboard, but win more than they lose at the betting window. Here are some other things to consider regarding betting on and against rookie head coaches throughout the NFL season:

Rookie head coaches have been far more proficient at covering point spreads on the road over the past decade. Here is the breakdown: Home games — 149-163-14 ATS (47.7 percent). Road games — 170-148-7 ATS (53.5 percent). It seems oddsmakers tend to shade lines against these rookie coaches on the road, wrongly assuming the pressure and difficulty of the road environments will affect the execution level.

As favorites of 6 points or more since 2011, rookie head coaches are 61-19 SU, good for 76.3 percent outright, but have gone just 33-46-1 ATS, a covering rate of just 41.8 percent.

Rookie head coaches also have struggled in the large underdog role, going 34-143 SU (19.2 percent) and 84-88-5 ATS (48.8 percent when catching 6 points or more since 2011).