Looking at 49ers' season by the numbers

This week, the 49ers' coaching staff flew to Mobile, Alabama to scout college players, coach the Senior Bowl and prepare for the future.

But part of preparation involves looking backward, specifically to 2018, and identifying where the 49ers need to improve. Figuring out where they excelled, where they struggled most and which issues could re-emerge next season if the organization overlooks them.

Sometimes, a team's biggest strength or weakness isn't obvious. Football has an endless number of variables to examine and consider. Teams spend weeks going through all of them and dissecting the previous season.

Here are the 10 stats that defined the 49ers in 2018, and what these stats could mean for them in 2019.

Stat No. 1: The 49ers' offense ranked ninth in yards per play from their own 21-yard line to midfield.

Kyle Shanahan is a genius at creating offense from his territory.

Despite losing starting quarterback Jimmy Garoppolo for 13 games and starting running back Jerick McKinnon for the entire season, the 49ers averaged 6.62 yards per play from their 21-yard line to midfield. They averaged more than the Pittsburgh Steelers, who have a future Hall of Fame quarterback, Ben Roethlisberger, and two great wide receivers - Antonio Brown and Juju Smith-Schuster.

When offenses have the ball in their own territory, opposing defenses typically play soft, conservative, vanilla coverage schemes, which Shanahan exploits as well as any coach in the league. This is his biggest strength.

Stat No. 2: The 49ers' offense ranked 18th in yards per play from midfield to the red zone.

When offenses cross midfield and have the ball in the opponent's territory, defenses begin to blitz more often and call tighter, more aggressive coverages. Shanahan doesn't attack these defenses as well you'd expect.

From midfield to the red zone, the 49ers' offense averaged just 5.35 yards per play - slightly below the league average of 5.5. The same plays Shanahan called from his side of the field didn't work nearly as well on the other team's side of the field. He would be wise to create different offensive plans based on field position, if he doesn't already.

Stat No. 3: The 49ers offense ranked dead last in red-zone efficiency.

The closer Shanahan's offense gets to the goal line, the less effective it becomes. The 49ers scored touchdowns during just 41.2 percent of their trips to the red zone – the worst rate in the NFL.

The issue was the running game. The 49ers scored just five rushing touchdowns in 73 attempts from the red zone, or one rushing touchdown every 14.7 tries. The league average was one rushing touchdown every 3.8 tries. The problem could lie with the running backs (they're small), or the offensive linemen (they're small, too), or the offensive scheme, or a combination of the three.

Stat No. 4: The 49ers' offense ranked 17th in third-down-conversion percentage.

All four teams that reached the conference championship round of the playoffs ranked top 10 in third-down conversion percentage. The 49ers have to find a way to improve.

Garoppolo's return should help, but in 2018 his quarterback rating on third down was just 48.1. He needs help, too, specifically from players who can beat tight coverage and catch contested passes. None of the 49ers' top-five targets on third down caught more than 57 percent of the passes that came their way in 2018.

Stat No. 5: The 49ers' offensive line gave up 125 quarterback hits.

Garoppolo needs a clean pocket to deliver accurate passes on third down. None of the 49ers' quarterbacks had a clean pocket in 2018.

Four of the 49ers' five starting lineman will be under contract in 2019. Only right guard Mike Person will be a free agent. The 49ers might consider replacing him with a high draft pick or a quality free agent, because they can't allow Garoppolo to take a beating, especially his first season back from ACL surgery.

Stat No. 6: The 49ers' defense broke up only 39 passes.

The 49ers' defense set an embarrassing NFL record in 2018 - fewest interceptions in a season. The 49ers recorded only two. They also ranked 32nd out of 32 teams in pass breakups.

The problem partially is schematic. The 49ers primarily use zone coverages, which concede short throws. Only after the reception do the defensive players run to the ball carrier and tackle him. The 49ers might consider using more man-to-man coverage in 2019, so their defensive players can chase receivers and contest passes while the ball is in the air.

Stat No. 7: The 49ers, defense ranked 26th in red zone.

The 49ers' preference for zone coverage particularly hurt them in the red zone. Because when they concede short passes near the goal line, those short passes become touchdowns.

The 49ers gave up 26 touchdown passes and an average quarterback rating of 107.1 in the red zone. Most quarterbacks play worse in that area of the field. Against the 49ers, they played better. Perhaps that's why the 49ers hired a new passing game coordinator, Joe Woods, for the defense this offseason.

Stat No. 8: The 49ers' turnover differential was negative-25.

That was the worst differential in the NFL. The 49ers gave the ball away 32 times, and took it from the other team just seven times. Next season, Shanahan can call safer passes that lead to fewer interceptions. The 49ers offense ranked 30th in interception percentage in 2018.

And on defense, general manager John Lynch can add more players who have a history of forcing turnovers. Players unlike Reuben Foster, the former 49ers linebacker whom Lynch took in the first round of the 2017 draft, even though Foster hadn't forced a turnover since high school. He hasn't forced a turnover in the NFL yet, either.

Stat No. 9: The 49ers' special teams ranked 21st, according to Rick Gosselin. Gosselin is a sports columnist for the Dallas Morning News, who has graded special teams the past 39 seasons. He grades each unit on 22 categories.

The 49ers excelled in two categories: kicking and kick returns. Robbie Gould is one of the most accurate kickers in the league, and Richie James is a legitimate weapon as a kickoff returner, one of only five players who returned a kickoff for a touchdown in 2018.

But the 49ers struggled punting, returning punts and covering kickoffs. Punter Bradley Pinion averaged just 43.7 yards per punt, which ranked 28th. He has one of weakest legs among NFL punters.

The 49ers also fumbled four punts in 2018 and ranked 29th in yards per punt return. And their kickoff coverage unit gave up 24.5 yards per kickoff return - eighth worst in the NFL.

Special teams hurt the 49ers' field position in 2018. They would benefit big time from adding a quality punt returner.

Stat No. 10: Seventeen 49ers spent time on injured reserve.

The 49ers have a durability problem. Some of their recent injuries may have been flukes, but some were predictable. Take Jimmie Ward, who missed the final five games with a broken forearm. Before the season, the 49ers picked up the fifth-year option of his contract, which paid him $8.5 million. They picked it up even though Ward missed eight games with a broken forearm in 2017. History repeated itself in 2018.

If the 49ers want a healthier team in 2019, they might consider signing healthier players.